Category Archives: Climate Science

Oct. 4th: Community Climate Courage Showing of The Wisdom to Survive

October 4th, 2:00 pm
The Alliance Center
1536 Wynkoop Street, Suite 100, Denver CO

Join CEA and the Climate Courage Resilience Circle for a film screening and discussion of The Wisdom to Survive. This film accepts the consensus of scientists that climate change has already arrived, and asks: what is keeping us from action? The film explores how unlimited growth and greed are destroying the life support system of the planet, the social fabric of the society, and the lives of billions of people.

Join the event on Facebook!

Will we have the wisdom to survive? The film features thought leaders and activists in the realms of science, economics and spirituality discussing how we can evolve and take action in the face of climate disruption. They urge us to open ourselves to the beauty that surrounds us and get to work on ensuring it thrives.

Amongst those featured are Bill McKibben, Joanna Macy, Roger Payne, Richard Heinberg, Gus Speth, Stephanie Kaza, Nikki Cooley and Ben Falk.

Suggested donation: $7. No one will be turned away for lack of funds, but we gratefully accept contributions to support this initiative!

Seating is limited. Register here to attend the event.

Climate Change: The Latest Science, Why It’s Serious, & What You Can Do About It

7 pm to 9 pm
Tuesday, September 8th, 2015
Wolf Law Building, Room 204
2450 Kittredge Loop Road, Boulder, CO

Join Clean Energy Action and the Colorado Renewable Energy Society (CRES) for an explanation of the latest science about climate change and what we can do about it, featuring:

Dr. Chuck Kutscher

Director of the Buildings and Thermal Systems Center
National Renewable Energy Laboratory

Discussion will focus on:

–  How we know our climate is changing
– Why it’s clear that we are causing climate change
– What we can do to address  climate change
– How we can respond with the needed solutions today

Join the Meetup event and share it with your friends!

This meeting is free for CRES members and $5 for non-members.

The What and Why of Carbon Budgets

If you’ve been paying much attention to the climate policy discussion over the last few years, you’ve probably heard mention of carbon budgets, or greenhouse gas (GHG) emissions budgets more generally. Put simply, for any given temperature target there’s a corresponding total cumulative amount of greenhouse gasses that can be released, while still having a decent chance of meeting the target. For example, the IPCC estimates that if we want a 2/3 chance of keeping warming to less than 2°C, then we can release no more than 1000Gt of CO2 between 2011 and the end of the 21st century.

The IPCC estimates that if we want a 2/3 chance of limiting warming to less than 2°C, then we can release no more than 1000Gt of CO2 equivalent between 2011 and the end of the 21st century.

The reason the IPCC and many other scientist types use carbon budgets instead of emissions rates to describe our situation is that the atmosphere’s long-term response to GHGs is almost entirely determined by our total cumulative emissions. In fact, as the figure below from the IPCC AR5 Summary for Policymakers shows, our current understanding suggests a close to linear relationship between CO2 released, and ultimate warming… barring any wild feedbacks (which become more likely and frightening at high levels of atmospheric CO2) like climate change induced fires vaporizing our boreal and tropical forests.

Carbon Budget vs. Cumulative Warming
Figure SPM.5(b), from the IPCC AR5 Summary for Policymakers.

What matters from the climate’s point of view isn’t when we release the GHGs or how quickly we release them, it’s the total amount we release — at least if we’re talking about normal human planning timescales of less than a couple of centuries. This is because the rate at which we’re putting these gasses into the atmosphere is much, much faster than they can be removed by natural processes — CO2 stays in the atmosphere for a long time, more than a century on average.    We’re throwing it up much faster than nature can draw it down.  This is why the concentration of atmospheric CO2 has been marching ever upward for the last couple of hundred years, finally surpassing 400ppm this year.

So regardless of whether we use the entire 1000Gt budget in 20 years or 200, the ultimate results in terms of warming will be similar — they’ll just take less or more time to manifest themselves.

Unfortunately, most actual climate policy doesn’t reflect this reality.  Instead, we tend to make long term aspirational commitments to large emissions reductions, with much less specificity about what happens in the short to medium term.  (E.g. Boulder, CO: 80% by 2030, Fort Collins, CO: 80% by 2030, the European Union: 40% by 2030).  When we acknowledge that it’s the total cumulative emissions over the next couple of centuries that determines our ultimate climate outcome, what we do in the short to medium term — a period of very, very high emissions — becomes critical.  These are big years, and they’re racing by.

Is 1000Gt a Lot, or a Little?

Few normal people have a good sense of the scale of our energy systems. One thousand gigatons. A thousand billion tons. A trillion tons. Those are all the same amount. They all sound big. But our civilization is also big, and comparing one gigantic number to another doesn’t give many people who aren’t scientists a good feel for what the heck is going on.

Many people were first introduced to the idea of carbon budgets through Bill McKibben’s popular article in Rolling Stone: Global Warming’s Terrifying New Math. McKibben looked at carbon budgets in the context of the fossil fuel producers. He pointed out that the world’s fossil fuel companies currently own and control several times more carbon than is required to destabilize the climate. This means that success on climate necessarily also means financial failure for much of the fossil fuel industry, as the value of their businesses is largely vested in the control of carbon intensive resources.

If you’re familiar with McKibben’s Rolling Stone piece, you may have noticed that the current IPCC budget of 1000Gt is substantially larger than the 565Gt one McKibben cites. In part, that’s because these two budgets have different probabilities of success. 565Gt in 2012 gave an 80% chance of keeping warming to less than 2°C, while the 2014 IPCC budget of 1000Gt would be expected to yield less than 2°C warming only 66% of the time. The IPCC doesn’t even report a budget for an 80% chance. The longer we have delayed action on climate, the more flexible we have become with our notion of success.

Unfortunately this particular brand of flexibility, in addition to being a bit dark, doesn’t even buy us very much time. If we continue the 2% annual rate of emissions growth the world has seen over the last couple of decades, the difference between a budget with a 66% chance of success and a 50% chance of success is only ~3 years worth of emissions. Between 50% and 33% it’s only about another 2 years. This is well-illustrated by some graphics from Shrink That Footprint (though they use gigatons of carbon or GtC, instead of CO2 as their unit of choice, so the budget numbers are different, but the time frames and probabilities are the same):


Like McKibben’s article, this projection is from about 3 years ago. In those 3 years, humanity released about 100Gt of CO2. So, using the same assumptions that went into the 565Gt budget, we would now have only about 465Gt left — enough to take us out to roughly 2030 at the current burn rate.

There are various other tweaks that can be made with the budgets in addition to the desired probability of success, outlined here by the Carbon Tracker Initiative.  These details are important, but they don’t change the big picture: continuing the last few decades trend in emissions growth will fully commit us to more than 2°C of warming by the 2030s. 2030 might sound like The Future, but it’s not so far away.  It’s about as far in the future as 9/11 is in the past.

It’s encouraging to hear that global CO2 emissions remained the same in 2014 as they were in 2013, despite the fact that the global economy kept growing, but even if that does end up being due to some kind of structural decoupling between emissions, energy, and our economy (rather than, say, China having a bad economic year), keeping emissions constant as we go forward is still far from a path to success. Holding emissions constant only stretches our fixed 1000Gt budget into the 2040s, rather than the 2030s.

If we’d started reducing global emissions at 3.5% per year in 2011… we would have had a 50/50 chance of staying below 2°C by the end of the 21st century. If we wait until 2020 to peak global emissions, then the same 50/50 chance of success requires a 6% annual rate of decline.  That’s something we’ve not yet seen in any developed economy, short of a major economic dislocation, like the collapse of the Soviet Union.  And unlike that collapse, which was a fairly transient event, we will need these reductions to continue year after year for decades.


The Years of Living Dangerously

We live in a special time for the 2°C target.  We are in a transition period, that started in about 2010 and barring drastic change, will end around 2030.  In 2010, the 2°C target was clearly physically possible, but the continuation of our current behavior and recent trends will render it physically unattainable within 15 years.  Barring drastic change, over the course of these 20 or so years, our probability of success will steadily decline, and the speed of change required to succeed will steadily increase.

I’m not saying “We have until 2030 to fix the problem.”  What I’m saying is closer to “We need to be done fixing the problem by 2030.”  The choice of the 2°C goal is political, but the physics of attaining it is not.

My next post looks at carbon budgets at a much smaller scale — the city or the individual — since global numbers are too big and overwhelming for most of us to grasp in a personal, visceral way.  How much carbon do you get to release over your lifetime if we’re to stay with in the 1000Gt budget?  How much do you release today?  What does it go toward?  Flying? Driving? Electricity? Food?  How much do these things vary across different cities?

Featured image courtesy of user quakquak via Flickr, used under a Creative Commons Attribution License.

Colorado Wildfire Climate Change Fail

The past couple of years have been rough on Colorado, in terms of climate change related disasters.  First a couple of record setting wildfire years, and then floods of “biblical” proportions.  At a gut level we know we have to respond, but our public discourse is having trouble addressing the root cause directly.  Instead we’re dancing around the issue, and failing to either adapt adequately to our new reality or to mitigate further climate change.


Bills related to both the wildfires and last fall’s floods have been wending their way through our state legislature, and last week legislators and the governor held a press conference to highlight some of them, and a lot of the resulting commentary seemed to focus on the safety and well being of the firefighters and other emergency services workers that risk their lives on our behalf.  Largely absent from the discussion were the strong measures that the Governor’s wildfire task force put forward in the fall. They included:

  • Creating a wildfire risk map, and rating all properties on a scale of 1 to 10,  requiring that risk designation to be disclosed before any property sale, and making it available to insurance companies for use in setting their rates.
  • Charging those living in the “wildland urban interface” a fee based on their risk exposure, that would be used to defer some of the additional public costs incurred in protecting their private property.
  • Creating fire-resistant building codes for high risk areas, affecting both the materials used in construction, and requirements for defensible space around buildings.

Make no mistake: these are climate change adaptation measures, and Colorado has rejected them.

Firefighters in Waldo Canyon

As the Denver Post reported in September: developers didn’t like the idea of increased construction costs; the real-estate industry didn’t like the idea of making a lucrative market much less attractive; homeowners in high risk areas certainly didn’t like the idea of paying for the risks they’ve taken on, or making those risks transparent to potential buyers of their property.

Would the discussion be any different if people understood that the wildfire frequency and intensity is likely to just keep increasing as climate change marches on?  This is about as close as the article from September gets to mentioning climate change:

Colorado terrain ravaged by wildfire has quadrupled from 200,000 acres in the 1990s to nearly 900,000 acres in the 2000s.  “Scientists tell us this pattern isn’t going to change,” Hickenlooper said.

Why is the “pattern” there in the first place?  What kind of scientists was the Governor was talking to?  None of the press articles linked to from this post mention climate change even once, despite universally pointing out the trend.  For example: As Colorado wildfires continue to worsen, only moderate laws proposed.  And why are they worsening?  No comment.  Even the wildfire task force’s report mentions climate change only once in 80 pages.

Waldo Canyon Fire Aftermath

The only big risk factor we’ve talked about directly is where we choose to build our homes.  This is an important discussion too.  The overall wildfire risk — at least to human lives and property — is something like:

(human risk) = (area burned) x (pop. density in high risk areas)

Climate change will in large part determine how much of our state burns each year, but we have a choice about how many people and how much property to put in areas subject to burning.  Reducing our exposure to the increasing wildfire risk is an adaptation to climate change — an alteration of our behavior, in light of the expected risks going forward.  For the moment at least, we seem unwilling to listen to the warnings.

But hey, at least the state had a conversation, and decided not to do anything.

Cause and Effect

So what are the causes?  According to the US Forest Service, the enormous bark beetle kill is due in part to warmer winters, resulting from climate change.  These forests filled with dead trees are warm and dry for longer each year, lengthening the western US fire season by about 2 months.  So it’s perhaps unsurprising that the number of large wild fires per year has already increased from 140 in the 1980s, to 250 in the first decade of the 2000s.  This infographic from the Union of Concerned Scientists is a good cartoon summary:

Western Wildfires and Climate Change

(see this paper for the references behind the infographic)

The third panel is probably the scariest for Colorado.  The dark red swath covering most of the western half of the state means that we expect more than six times as much land to burn each year in the near future, with just 1°C (1.8°F) of additional warming — and as Kevin Anderson and many others have pointed out, it is virtually certain that we will see another 1°C of warming… if not 3°C, or even more.

So our elected representatives are right to be concerned about increased risk from wildfires, and about the safety of the firefighters who try to protect us from those fires.  But we’re still missing the point:  We control our exposure to risk locally, and we control the magnitude of that risk globally.


Policies aimed at avoiding or reducing climate change (like putting a price on carbon) are mitigation efforts.   We’re not talking about them much, even in the context of an obviously climate mediated risk like wildfires.  This is bad.  If we can’t have a conversation about what’s increasing the wildfire risks, how can we hope to respond appropriately?  Is our refusal to respond to change related to our refusal to accept the cause of the change?  Or is it more a kind of landscape amnesia — an inability to even see the change?  Are we going to forget what normal fire seasons looked like, in the same way that we’ve started to forget what a normal winter feels like:


Double Climate #Fail

Right now we’re managing to fail doubly with respect to climate change.  We are both unwilling to adapt to the foreseeable risks, and unwilling to even mention that these risks are linked to our greenhouse gas emissions, let alone talk about what we might do to mitigate those emissions and the risks that they create.

If we really care about our firefighters, if we really are intent on avoiding ever more costly and tragic conflagrations in our state, we need to both adapt and mitigate.  We need to start building for a warmer world now, and we need to stop warming the world as quickly as possible.

If you agree, look up the contact information for your Colorado state legislators and let them know.