global warming

Climate change and debate

An interesting article about the amazing climate change humans are causing was published by the UNC Charlotte campus newspaper back in Spring 2014, but it’s worth re-visiting as our atmosphere once again reached 400 ppm CO2 concentration. The piece was published as a point-counterpoint discussion, but as many scientists (include myself) point out, science is not about considering all sides – it’s about considering what the evidence suggests. I wrote a letter in response to the viewpoint that climate change is no big deal. If the evidence from multiple experiments/studies suggests a single point is true, then that’s where the scientific community will tend towards when explaining that science. As the evidence builds and builds with no one finding counter-evidence, the conclusions become more and more robust*. If the evidence suggests mixed or nuanced results, then scientists will talk about that science as inconclusive and continue to try to design better experiments or get more data or both. Most importantly, perhaps, if counter-evidence arises repeatedly, scientific conclusions will change in response. Science is a beautiful, self-correcting process.

In Spring 2014, I sat down with a Niner Times reporter and Twitter friend Ed Averette and talked with him about how I see climate science, and how I talk about the science of climate change in my classroom (most prominently in ESCI 3101, Global Environmental Change). I had a lot to say, mostly because I had just returned from a wonderful conference called the Carolinas Climate Resilience Conference in April 2014, where I talked about Climate Change in the University Classroom (presentation here!), and I met some amazing outreach-oriented people (Kirstin Dow, Greg Carbone, Jim Gandy), and learned a climate change song that could be played on a dulcimer sung by this NPS Ranger. The article Averette wrote is available online and includes a figure I made for my class lectures.

The amazing correlation between Earth's temperature and CO2 concentration in the atmosphere, as derived from multiple ice core datasets shown in the graph itself.

The amazing correlation between Earth’s temperature and CO2 concentration in the atmosphere, as derived from multiple ice core datasets shown in the graph itself.

Another Niner Times reporter, Louis Aiello, provided the (journalistic) opposing viewpoint that there is no need to panic when it comes to the present-day climate change and his article is available online as well. Both articles are worth reading since they echo the innate concern we have for our planet, but that at the same time, the problem can feel overwhelmingly large**. Aiello never spoke with me, or as far as I could tell, any expert in the field of climate science, so of course I agree more with the approach Averette used, and found myself strongly disagreeing with Aiello’s article. I wrote a letter to the Niner Times in response to Aiello’s article, and I wrote a shorter version of that letter as well for the print newspaper. I did this because I often think about this artificial public debate that exists in the face of a broad scientific consensus about many points regarding the present-day climate change, and I also think that scientists need to speak up when they know about a topic.
Screenshot of the print version of my letter that had a limited number of words I could include.  Hence the online letter is longer.

Screenshot of the print version of my letter that had a limited number of words I could include. Hence the online letter is longer.


*Gravity is a good example. Go measure the acceleration if you want, but you’re likely to find the same thing any scientist will find. Acceleration due to gravity is 9.8 meters per second every second that an object falls. Thus, this is essentially a fact in our world, but it arose from evidence, not our gut feeling.

**This philosophy of how a single person drawing from a common resource scales up to major problems is known as the Tragedy of the Commons, which has been spoken about eloquently by many many people, including wikipedia.

Climate change and 400 ppm carbon dioxide

In the great carbon cycle that is at work on our planet, carbon dioxide (CO2) gas concentration in our atmosphere, as measured in the most famous observation site in the world (Mauna Loa, Hawaii, home of the Keeling Curve), has risen again above 400 parts per million, or 400 ppm for short. mlo_two_years-2015-01-12This happened in 2014 before CO2 dipped back below 400 ppm, and while 400 ppm is an arbitrary choice to focus on, round numbers typically get more attention than, say, 397 ppm. Think about a baseball player’s batting average, which is hits divided by at bats. Somehow a 0.299 (or “299”) batting average is perceived as worse than a 0.300 (300) batting average, but really, it’s the difference of a few hits (or at bats) in the course of a season. Ted Williams hit 406 in 1941. 185 hits in 456 at bats. 3 fewer hits, and he would have hit 399, and the world would’ve sighed. 3 hits! Back to CO2. I’ll suggest, like many others, that 400 ppm is a good place to step back and think.

What is the carbon cycle?

IPCC AR5 Figure 6.1 is a nearly perfect capture (as it should be given the expertise that developed the figure!), but I boiled away the beauty to a more practical figure for my classes. carbon-cycle-boiled The reason that CO2 goes up and down in any given year is mainly because the Earth breathes in and out. When the Earth breathes in, plants draw CO2 from the air and convert it to plant carbon via photosynthesis. As a result CO2 concentration in the atmosphere goes down. When the Earth breathes out, plants release CO2 into the air via that respiration, the process of decomposition that acts in the opposite direction of photosynthesis. CO2 concentration in the atmosphere then goes up. The breath results in a steady rise in CO2 concentration from October to May, and a steady decrease from June to September. As you would expect, the rise and fall are essentially reversed in when they occur in the Southern Hemisphere, and this is evident in the data as well. As you might also surmise, in the Northern Hemisphere, the enormous number of seasonal plant growth/decay results in a bigger “breath” than in the Southern Hemisphere. Check the graph here to see that hemisphere difference.

The Keeling Curve, and CO2 concentration in general, is a way to “see” a part of the Earth’s carbon cycle, which are all the physical/chemical/biological/geological (biogeochemical, for short) processes that exchange carbon. The exchanges between carbon “reservoirs” (for example, the atmosphere and the land in the figure above) happen at different rates and magnitudes. Oceans store enormous amounts of carbon from CO2, and rocks store even more. The atmosphere is relatively carbon-free, but we are burning carbon from rock reservoirs (fossil fuels), and burning is a combustion chemical reaction that produces many carbon-containing gases and particles, but most fundamentally water vapor and CO2. This CO2 goes into the atmosphere and stays there for a long time. Water vapor goes into the atmosphere too, but leaves the atmosphere within a couple of weeks via precipitation. As a result, the year to year variability shows the Earth’s breath (land-atmosphere exchange), but the long-term trend shows that CO2 concentration itself is increasing when you compare the average from one year to one from a previous year. That long-term trend is showing how more and more carbon from CO2 is being stored in the atmosphere reservoir of the carbon cycle.

We are FORCING the carbon cycle to change by changing the amount of carbon in the atmosphere. That 400 ppm concentration value is a measure of how much carbon from CO2 (in units of mass, like kilograms or pounds) is in the atmosphere. The change in concentration is a measure of how much carbon from CO2 has been put into the atmosphere (again, in units of mass). The pre-industrial concentration of CO2 was about 280 ppm, so 120 ppm has been added to the atmosphere reservoir in the carbon cycle. It’s relatively easy to show that +120 ppm is equal to 284 billion tons of carbon added to our atmosphere.

Most of that 120 ppm is from human activities of fossil fuel burning (moving carbon from rock reservoir) and from deforestation (moving carbon from land reservoir), and 400 ppm is, as far as humans are concerned, completely unprecedented. ipcc-ar5-wg1-Fig6-08 At no time in the past 800,000 years, through several ice ages and enormous climate changes (figure at bottom), has the planet had concentrations of anything close to 400 ppm. Furthermore, it is quite clear from scientific and anthropologic evidence (at least!) that human civilization has evolved in a period of relative stability in Earth’s climate history. CO2 concentration has largely remained around 280 ppm until the last 100 years or so. Evidence that scientists have collected suggest that CO2 and temperature track each other. This is fundamentally why most climate scientists, and most scientists in general, are concerned about short and long term futures.

Humans can adapt and we will have to adapt to some degree, but the changes we are imposing on the planet through the carbon cycle are much faster than anything that we have an analog for in the past through naturally-driven climate changes. This is where carbon mitigation strategies are so critical, and why everyone is talking about the EPA Clean Power Plan, COP20 Lima, China-USA negotiations, and the upcoming COP21 Paris negotiations. These negotiations are about whether humans can live on the world without altering it in ways that more than likely is detrimental before being beneficial. Right now, the science says we are not very good tenants. With 400 ppm CO2, we are breathing air with more CO2 in it than any other human or proto-human has ever breathed. It’s not poisoning us directly, but the increased CO2 is changing how the Sun and Earth-Atmosphere system are interacting with each other. We are forcing the planet to warm as more electromagnetic radiation is absorbed by the unusual excess of greenhouse gases in the atmosphere. The warmth is changing everything, and it will continue.
co2-800k-present

Voting for action on global environmental change

global-201101-201112As real as global warming (figure above from NOAA NCDC) is, and as much as we expect that the science has done enough, one US lawmaker recently said

I am for global action on climate change. I am a proud supporter and very anxious for the U.S. to participate globally. But I think if you look at the current makeup of the U.S. Senate, it’s very difficult.

This is a quote from Senator Ben Cardin (D-Md.) that I drew from a recent article that I’ll get to below. As I close off discussions with 28 undergraduate students of Earth Sciences, Geology, Meteorology, and Economics this semester in my Global Environmental Change course, the questions that permeate their responses to readings* we went over in class are

1. WHAT CAN WE DO?
2. WHY AREN’T WE DOING ANYTHING?

I bring a lot of current discussion into the classroom – more than the previous iteration of my course and I await my course reviews and student comments to better understand which materials resonated and which did not. In the meantime, my answer to the driving questions for the future of our state and country is simple: VOTE. Vote for the legislators that work on issues that you think benefit the global community.

The simplicity in my answer is partly because I don’t have a better answer, but partly because this is where the science stands. Namely, science has arrived at robust conclusions based on decades of intense research by communities of experts, most recently evidenced by the full report of the IPCC. Earth scientists keep working on issues because we are interested in what makes the physical world tick, and just like any community of professionals, the majority of us work on science that is relevant. The most relevant Earth science is climate science. I think it is safe to say that most Earth scientists want to see some actual climate action rather than the empty words that most that most of the action statements by politicians have amounted to so far. A widely-cited scientific paper about a way to visualize and break down carbon mitigation strategies into manageable parts said that the choice is simple: Act or delay.

If we want action, we cannot rely solely on science and engineering – we need policy makers. Policy makers are elected by people. So if my students want to help, vote. If citizens in general want to help, then vote. An interesting report by Lisa Friedman at Energy and Environment News included quotes from US lawmakers about the upcoming 2015 Paris climate meeting that many were hoping would be much farther along after this year’s Poland climate meeting. I’ll include several below:

It will be difficult to get a treaty passed in 2015 in the U.S. Senate as it is presently constituted

———————————–> Sen. Ed Markey (D-Mass.)

Keep our eyes on the prize of creating an ambitious, effective and durable agreement. Insisting that only one way can work, such as an agreement that is internationally binding in all respects, could put that prize out of reach.

———————————–> U.S. Special Envoy for Climate Change Todd Stern

[A binding agreement is] not going to go anywhere. It’s dead on arrival… [EPA limits on CO2 emissions from future power plants are] hurting our economy on a daily basis.

———————————–> Sen. John Barrasso (R-Wyo.)

There is a lot of difference of opinion among very educated people on the science [of global warming]. [On whether a binding agreement would pass the Senate: ] I kind of doubt it. There is still a legitimate question of science, and you can’t brush that away.

———————————–> Sen. Orrin Hatch (R-Utah)

I think this [a global climate treaty] is an issue that can flip very quickly. [An EPA regulation, for example, would] put a lot of costs on polluters and cause them to rethink the wisdom of an economywide carbon fee. If we can organize the armies on our side, it’s a rout. We just haven’t bothered to organize them. [The fact that climate is back in the political discussion and may be in 2014 means] that adds up to 2015 being a pretty good year.

———————————–> Sen. Sheldon Whitehouse (D-R.I.)

This problem is global, not just related to any one country or only one region. We need an international effort, and I think there’s growing support for that in the United States.

———————————–> Rep. Henry Waxman (D-Calif.)

We need to set a good example to the rest of the world. That way, when we call on China and India and other big emitters, we can say not only ‘Do as I say,’ but ‘Do as I do.’

———————————–> Sen. Tom Carper (D-Del.)

Increasingly, the U.S. is being viewed as a leader. Especially if the administration takes action on coal-fired power plants, I think it will be very hard, then, for China and India to say the U.S. is not acting.

———————————–> Sen. Ed Markey (D-Mass.)

[Action might require] some kind of catastrophe… I think [global warming and subsequent impacts are] real, and I think that we should continue to explore our options to reduce the effects of it. [He has not liked] anything I’ve seen lately [about how the UN climate process has influenced US lawmakers.] [Still, he conceded,] I don’t think talking hurts. It probably helps.

———————————–> Sen. John McCain (R-Ariz.)

Are pathways opening up? Has Obama been able to set up his position strongly enough to promote policies that are in line with the science? Well, it comes back to the simple solution: Vote for what you believe. I would argue that your political party – socially or economically – is not the relevant part of a vote that supports climate change policy.

As Professor Andrew Dessler argues in his book, and as many other climate and climate policy scientists argue, the decision to move away from energy sources with high carbon emissions is completely reversible – if the climate science summarized in the IPCC reports is entirely wrong or even partly wrong about carbon cycle science,

Figure 2 from Chapter 6 (Carbon and Other Biogeochemical Cycles) FAQ 6.1 of IPCC AR5 Working Group 1.  Shows that some fraction of a 5000 GtC pulse of carbon emissions - on scale with a pulse from burning all fossil fuel reserves - would affect the atmosphere for 1,000s to 100,000s of years.  Roughly 40% of the pulse would remain in the atmosphere even after 2000 years.

Figure 2 from Chapter 6 (Carbon and Other Biogeochemical Cycles) FAQ 6.1 of IPCC AR5 Working Group 1. Shows that some fraction of a 5000 GtC pulse of carbon emissions – on scale with a pulse from burning all fossil fuel reserves – would affect the atmosphere for 1,000s to 100,000s of years. Roughly 40% of the pulse would remain in the atmosphere even after 2000 years.

we can always go back to burning the least expensive energy sources without regard to the environment. But if climate science is even close to right, then we are facing irreversible changes (see the figure above) to the carbon cycle that will affect the Earth for centuries, millenia, and even further.

As I told my students, the questions that we face are civilization scale (echoing Rep. Waxman’s quote above). Human civilization emerged as a presence on Earth somewhere between 20,000 and 200,000 years ago. I’m no archaeologist, so that number isn’t particularly important. The point is that dinosaurs managed to survive for 165 million years on Earth and evolve into the Cretaceous Period species that we know and love (tyrannosaurus rex, triceratops, etc.). It sure would be nice to think that our advanced technology means we can learn to live in harmony with the planet longer than the dinosaurs! Considering that the dinosaurs were finally offed by a meteorite, I’d say we have a lot to prove still.

*readings from Elizabeth Kolbert, Andrew Dessler, IPCC AR4 and AR5, news posts from New York Times and Washington Post, and multimedia presentations such as Thin Ice, Earth The Operators Manual, and data visualizations and tools focusing on climate-relevant data like carbon emissions, temperature records, and climate model projections

Tracking and targetting emissions from power plants

Speaking as a part of a press release about power plant carbon emissions in NC.

Speaking as a part of a press release about power plant carbon emissions in NC.

As my students probably know by now, I think an important point when discussing or even thinking about how to deal with the combination of our hunger for energy and global warming is to remember the scales of the problem. There are two important scales to consider in every discussion of global warming: time and space. The adjectival forms would be “temporal” and “spatial”. The super-cool adjective, which I probably overuse, is “spatiotemporal”. Spatiotemporal analysis is critical to understanding global warming and what it means in any single location on Earth. The temporal scale is highlighted over and over again right now because of the global warming “pause”, which as any analysis or background research should reveal, is nothing more than a pause and that plenty of research is underway and done that helps to understand yet another small surprise in the complex Earth system. One part of the problem of climate change that is not surprising is what is the cause. Carbon emissions from fossil fuel burning are the main culprit, so the prescription is simple: Stop burning fossil fuels. Hah! This comes back to our hunger for the energy stored deep in the Earth, so the answer is definitely not as simple as the prescription.

Me talking about the state of climate science with Graham Givens of Environment NC, Ronald Ross, local resident and Vice President of Stewart Creek Environmental Association, and reporters!

Me talking about the state of climate science with Graham Givens of Environment NC, Ronald Ross, local resident and Vice President of Stewart Creek Environmental Association, and reporters!

I provided some scientific feedback to an effort by Environment North Carolina a few weeks ago that I neglected to highlight on my research webpage (but I did on twitter), and I will expand on this a little now. Environment NC released a report of carbon emissions from power plants across the USA. Power plants (coal, natural gas) are required to track and report these emissions, so sometimes groups just need to put forth the effort in assembling these numbers into a coherent piece of writing, which is what Environment NC did. They found that 3 of the top 50 most serious carbon emitters were in the state of NC – they are all coal plants of course. Coal is still being burned even though Natural Gas is used more and more. The key findings, as Environment NC stated on their written press release, are:

  • The Marshall plant, near Lake Norman, emitted 10.1 million metric tons of pollution in 2011, the equivalent of 2.09 million cars.
  • Three of the most polluting power plants in the country are in North Carolina: Belews, Roxboro, and Marshall.
  • Belews Creek Power plant near Winston-Salem was the state’s biggest global warming polluter and 16th overall, emitting 13.8 million metric tons of carbon pollution, the equivalent of 2.9 million cars.
  • North Carolina’s power plants are the 12th most polluting in the country, producing as much carbon each year as 15 million cars.
  • North Carolina’s power plants are its single largest source of carbon pollution – responsible for 51% of the carbon pollution in the state.
  • The press release was at their news site, and they arranged a live release for media. I went to Frazier Park near the heart of the Queen City early in Septemeber to speak about the science, essentially relying on the discussion in IPCC AR4, which is what I discuss in my classes too. I spoke from the position of scientific evidence. The press release at Frazier Park made its way through state and city news outlets, and I thought the reporters did a great job with the write-ups. Here are some links:

    Charlotte Business Journal

    WSOC-TV in Charlotte

    NC Public News Service

    Charlotte Observer

    I think on the eve of the release of the first part of the IPCC Fifth Assessment Report, it’s important to remember that the solution to the problem of global warming, or at least the best way to mitigate the problems, begins at a local level. We have to remember that the carbon emissions in our backyard – which Environment NC highlighted – affect the entire world. CO2 lasts 100-1000 years in the atmosphere so CO2 from North Carolina will be absorbing infrared radiation for a long, long time. Maybe I’ll write an op-ed for the Observer.

    Activity on twitter

    I haven’t posted anything here for about a week – an eternity in the land of constant chatter (the internet). I’m working on a couple of publications, which take a lot of concentration, so that’s my main excuse. My secondary excuse is that I’ve been prowling around the twitter-verse. Science talk on twitter has been active! Hard to quantify, but just seeing how much many prominent climate scientists (defined by publications, say), advocates, and climate-related groups are posting makes me think that some of discussion that twitter is a good venue for quickly disseminating science are on the right track. Facebook always felt stilted to me and seemed more like something you do with friends and family then the general world. Twitter feels different, but like I said, it’s hard to quantify. The best hashtag I’ve been witness to has been #ActOnClimate in response to President Obama’s speech announcing his administration’s Climate Action Plan (PDF with more details) and also since then. #ActOnClimate was trending high all afternoon on the day of his speech, for example. So my recent posts have been at the level of tweets and that’s about it. Here is a snippet of my activity.

    Science, global warming, and education news:

    Dynamics of a still mysterious part of the Earth that is above sea level (of course the oceans have many more mysteries!):

    Back to my roots with aerosol research and the myriad of dampening effects these little particles have on phenomena:

    Are eating habits going to be forced to change? I’m not 100% convinced of this, but I am 100% worried if climate science suggests that hamburgers have to go!

    go to @brianmagi for more. If you have your own climate action plan going in the Charlotte area, I’d love to hear from you on twitter or email.

    The Climate Change Speech transcript and video

    Here’s an update from my post yesterday about the Climate Change Speech. Link to the video on Youtube via whitehouse.gov. The video is downloadable (mp4) so you can show students how a speech embodies leadership on an issue that will, in my opinion, define this and the next generation. Link to the transcript of the speech at Georgetown University.

    When I review the transcript, I think about the speech Margaret Thatcher gave to the UN in 1989. Thatcher opened her speech about global warming with the voyages of Charles Darwin. Obama opened his speech with the voyages to space by US astronauts.

    President Obama said on a hot summer day (92 F air, 67 F dewpoint means about 96 F heat index) in Washington DC in June 2013

    On Christmas Eve, 1968, the astronauts of Apollo 8 did a live broadcast from lunar orbit. So Frank Borman, Jim Lovell, William Anders — the first humans to orbit the moon -– described what they saw, and they read Scripture from the Book of Genesis to the rest of us back here. And later that night, they took a photo that would change the way we see and think about our world. It was an image of Earth -– beautiful; breathtaking; a glowing marble of blue oceans, and green forests, and brown mountains brushed with white clouds, rising over the surface of the moon. And while the sight of our planet from space might seem routine today, imagine what it looked like to those of us seeing our home, our planet, for the first time. Imagine what it looked like to children like me. Even the astronauts were amazed. “It makes you realize,” Lovell would say, “just what you have back there on Earth.”

    Prime Minister Margaret Thatcher said in November 1989

    During his historic voyage through the south seas on the Beagle, Charles Darwin landed one November morning in 1835 on the shore of Western Tahiti. After breakfast he climbed a nearby hill to find advantage point to survey the surrounding Pacific. The sight seemed to him like “a framed engraving”, with blue sky, blue lagoon, and white breakers crashing against the encircling Coral Reef. As he looked out from that hillside, he began to form his theory of the evolution of coral; 154 years after Darwin’s visit to Tahiti we have added little to what he discovered then.

    What if Charles Darwin had been able, not just to climb a foothill, but to soar through the heavens in one of the orbiting space shuttles? What would he have learned as he surveyed our planet from that altitude? From a moon’s eye view of that strange and beautiful anomaly in our solar system that is the earth? Of course, we have learned much detail about our environment as we have looked back at it from space, but nothing has made a more profound impact on us than these two facts.

    First, as the British scientist Fred Hoyle wrote long before space travel was a reality, he said “once a photograph of the earth, taken from the outside is available … a new idea as powerful as any other in history will be let loose”. That powerful idea is the recognition of our shared inheritance on this planet. We know more clearly than ever before that we carry common burdens, face common problems, and must respond with common action.

    And second, as we travel through space, as we pass one dead planet after another, we look back on our earth, a speck of life in an infinite void. It is life itself, incomparably precious, that distinguishes us from the other planets. It is life itself—human life, the innumerable species of our planet—that we wantonly destroy. It is life itself that we must battle to preserve.

    I could read those words over and over again and never feel any less attached to the idea of a global community and the potential role that science can play in achieving this goal. After yesterday, the goal seems attainable.

    President Obama takes the offensive on climate change

    Categories: Group News

    Wow. What a speech this afternoon by President Obama on the Georgetown University campus – and a beautiful follow up to his Inaugural Address in January and his State of the Union speech shortly thereafter – noting one satire piece that is worthy of watching. He stepped onto the stage at about 2pm Eastern time and delivered. The backbone was the announcement of the President’s Climate Action Plan (click for PDF). The papers were buzzing – Washington Post for example but there were many many more “responses” to the unveiling of the Climate Action Plan. Twitter was super active from about 2-5 pm Eastern time with #ActOnClimate trending high. I haven’t been around Twitter long enough to see the electricity flowing like this, but watching the speech and the tweets at the same time was pretty inspiring. Entertaining too. Twitter was like a race to see who could point out a quote by @BarackObama the fastest. Obama said a lot of great things, but I like this one.

    We don’t have time for a meeting of the Flat Earth society

    He pointed out that the Clean Air Act only promoted American innovation and did NOT destroy the economy, and noted that the Clean Air Act passed nearly unanimously with only ONE DISSENTING VOTE. Times have changed! He metaphorically referred to the economic potential of moving to clean energy as the building of a new engine, referring (I presume) to the innovation of the automobile industry in America throughout the 20th century. Clean energy is here in this country now. He said that 75% of wind energy is in Republican districts (!). The community organizer in our President emerged as he gave credit to past Republican efforts to help our environment – the EPA was created under the Nixon administration, for example.

    I haven’t found the transcript or the high quality video yet, but June 25, 2013 was a very memorable moment for the USA. I hope it marks the turning point and that the USA leads – like it should, says this US Citizen – the development of a global community around the issue of global warming. I’ll leave you with an amazingly long graphic from the White House page.climate_change_report_62513_final_0

    May 2013 climate in North Carolina and the world

    With global warming and all of the impacts, it’s very important to constantly consider the question of time and space scales. May 2013 is a good example for those of us living in the Southeastern USA or North Carolina. Namely, North Carolina’s normal-to-cool spring is not at all indicative of how the global temperature is evolving. Let’s see how we can quickly use NOAA NCDC graphs to figure this out.

    Global warming refers to the increase in average temperature of the entire Earth. The last part – the entire Earth – is the spatial scale. And that’s a huge spatial scale! When a scientist talks about global warming or that global warming has been detected, you have to step back and say WOW. What on Earth could warm an entire planet? coal_fired_power_plantOver long time scales, of course there are a number of possible reasons (changes in the Sun, Earth’s orbital shape/proximity around the Sun, plate techtonics), but these take so long, they aren’t relevant to the concept of global warming. Even my statement that What on Earth could warm an entire planet? should be more precise and say something like What on Earth could warm an entire planet over a relatively short time period? The simplest, if somewhat incomplete, answer is the combination of greenhouse gases and aerosols emitted into the atmosphere from human activities. Period.

    May 2013 analysis of global temperatures are trickling out. NOAA NCDC as always has a wonderfully complete report of climate news for May and for all previous months. My favorite part is the plethora of hyperlinks. NOAA NCDC should really be commended for their public outreach! Here is one of the figures from that webpage201305where you can see how different the Southeast USA is from the world in May 2013 – the world is shades of red, while the Southeast USA is shades of blue (cooler than normal). We’ve had a very pleasant spring in North Carolina. Pull back on the temporal (time) scale to see the March-April-May seasonal average201303-201305 and you can see that the cool spring extends well beyond May in terms of the anomaly. By this, I mean that the blues become deeper when you consider a three month period (March-April-May) and that implies without any quantitative work that March-April were more cooler-than-average. Pull back slightly further to the year-to-date rankings201301-201305and here you see that the Southeastern USA and in fact most of the USA and even Alaska have been right at the climatological normal (which for NCDC is the average temperature from 1981-2010). The short story is that North Carolina below average temperatures for the period from January to May, March to May or just plain old May are not indicative of global temperatures. The real question is why?

    CO2 trends from around the world

    Time series are profilic in climate science. This is a dataset that shows the how a measurement changes over some period of time. The best known in our world is the global warming time series displayed as the globally-averaged surface temperature trend, which is compiled from thermometer measurements. A few research groups worldwide maintain this analysis (NASA GISS, UK Met Office, NOAA NCDC). Since CO2 is in the news, and since there is variability from one measurement location to another, it is useful to see how the best-known station in Mauna Loa, Hawaii (source of the data shown in the Keeling curve graph). Once you navigate the shifting axes (y-axis on the right and left, and the time series begin at different points in the past) and digest the information visualized here, the graph below is very useful in quickly understanding variability in CO2 concentration from the northernmost latitudes to the southernmost, noting the latitude is listed under the three-letter station identifier but that the graph is arranged north to south.co2-globaltrendsThere is clearly a bias toward higher CO2 in the northern hemisphere compared to the southern hemisphere – CO2 is about 10-12 ppm higher near the north pole. This piece of information – this data – reflects the higher abundance of sources of CO2 in the northern hemisphere and the relatively slow transport times required for air to move across the equator (like a slow drip compared to the winds we feel every day in the USA). The graph also effectively conveys another dimension of information: Regardless of the specific location of CO2 measurement, the long-term trend is essentially the same worldwide, indicating that CO2 continues to accumulate in the atmosphere worldwide at about the same pace. The trend could relatively easily be quantified, but sometimes qualitative analysis is enough. From the webpage where I found the figure, the station identifiers are PTB = Point Barrow, LJO = La Jolla, MLO = Mauna Loa Observatory, CHR = Christmas Island, SAM = Samoa, and SPO = South Pole. You can also find some commonality in the stations at NOAA’s website. All in all, a great data visualization that can be done entirely in black-and-white!

    CO2 time line for May 2013

    The month of May is officially over, and perhaps the Earth is about to take a big breath in and begin to draw down CO2 from its year 2013 peak. The last tweets by @Keeling_curve showed a relatively (emphasis on relatively!) sharp decrease from May 29 to May 30 with CO2 falling from 400.33 ppm to 398.41 ppm, and then May 31 had variability that was too high as tweeted here. Funny side note was that for whatever reason, this “data too variable” drew the attention of one well-known (but not well-respected) blog, to which @Keeling_curve replied “see here“. Geez, you’d think seasoned bloggers would click a couple of web links before tweeting a question like that. The values of CO2 should start their annual decrease from the peak value in the Northern Hemisphere as the plant life in temperate and polar zones comes to life, but in the mean time, we’re living in the age of a 400 ppm CO2 world, which is very unusual in recent geological history, as discussed here and shown here. Here’s the time line of CO2 concentrations for this historic May 2013co2-2013-05which shows the weekly-averaged CO2 from the daily-averaged values posted on Twitter (ok, tweeted). The straight horizontal purple line is the monthly-averaged CO2 of 399.82 ppm (wow!), and the straight red line is the mystical 400 ppm CO2. I calculated the weekly-average as the value of the previous 7 days up. For example, May 15 weekly-average is the average of values from May 9 through May 15. The weekly-average ideally is 7 data points, but occasionally a daily-averaged value is not tweeted due to high variability in the data. From the figure you can see that we reached our first weekly-averaged CO2 concentration greater than 400 ppm on May 19. I actually thought that would be it for the year, but from May 24 to May 29, daily values were again well over 400 ppm. This brought the number of weekly-averaged values greater than 400 ppm up to 5. Roughly, about 33% of the days in May 2013 had CO2 greater than 400 ppm. The decline should begin soon with the annual minimum in September-October reaching values of about 394-395 ppm, noting that the annual minimum for 2013 will probably be very close to the maximum from only 2 years ago. Below is the data shown in the graph above. An impressive May, and one that will be recorded in the history books.

                           carbon dioxide (ppm)
    year    month   day     daily   weekly
    2013	5	1	*	399.61
    2013	5	2	399.29	399.40
    2013	5	3	*	399.40
    2013	5	4	399.68	399.49
    2013	5	5	399.54	399.50
    2013	5	6	399.52	399.51
    2013	5	7	399.71	399.55
    2013	5	8	*	399.55
    2013	5	9	399.73	399.64
    2013	5	10	399.4	399.60
    2013	5	11	399.46	399.56
    2013	5	12	399.41	399.54
    2013	5	13	400.16	399.65
    2013	5	14	399.91	399.68
    2013	5	15	399.74	399.69
    2013	5	16	400.25	399.76
    2013	5	17	400.04	399.85
    2013	5	18	399.8	399.90
    2013	5	19	400.15	400.01
    2013	5	20	399.73	399.95
    2013	5	21	399.91	399.95
    2013	5	22	399.85	399.96
    2013	5	23	399.88	399.91
    2013	5	24	400.09	399.92
    2013	5	25	400.2	399.97
    2013	5	26	400.53	400.03
    2013	5	27	400.27	400.10
    2013	5	28	400.06	400.13
    2013	5	29	400.33	400.19
    2013	5	30	398.41	399.98
    2013	5	31	*	399.97
    

    *data was too variable over the course of the day. no value was reported on twitter.