david

The thing that really gets me in the gut about global warming from fossil fuel combustion is how long it will last. Carbon mined from the deep Earth and injected into the “fast carbon cycle” of the atmosphere, ocean, and land surface will continue to affect atmospheric CO₂ concentrations, and climate, for hundreds of thousands of years into the future, unless we clean up the atmosphere ourselves.

It turns out that human emissions of the element mercury (Hg) will elevate mercury concentrations in the environment, and in upper trophic-level seafood, for thousands of years into the future. There are a lot of parallels to the carbon cycle. But, unlike the carbon cycle, the mercury cycle would be impossible to clean up.
[Read more…] about Mercury, the other geologically persistent planetary poison

The recent US election has prompted cries that the decision on Earth’s climate has now been irrevocably made, that the US has unilaterally decided to scrap the peak warming target from the Paris agreement of 1.5 ^oC. What do the numbers say? Is Earth’s climate now irrevocably fracked?

[Read more…] about Trump carbon and the Paris agreement

Guest post by John Crusius, Richard Gammon, and Steve Emerson

The scientific community is almost universally in agreement that climate change (and ocean acidification) are severe threats that demand a rapid response, with putting a price on fossil fuel CO2 emissions being a top priority. Far and away the single biggest contributor to climate change is CO2 emissions from fossil fuel combustion. Indeed, global CO2 emissions from fossil fuel emissions in recent years have been roughly ten times higher than emissions from the next largest global source, land use change, including deforestation (Le Quéré et al., 2015). Despite the small size of carbon fluxes from forests, enhancing carbon storage in forests is often discussed in WA state as a tool to fight climate change. There was one such claim in the Seattle Times OpEd from October 21 by Mathew Randazzo. We challenge these claims that forest carbon sequestration in WA state can significantly help solve climate change. Randazzo does not spell out in any detail what he means. As always, details matter in such discussions, as the science is complex. We focus here on some of the best available science on the climate and carbon storage impacts of forests, and provide references at the bottom of this article from some of the premier scientific journals in the world.

[Read more…] about Carbon storage in WA state forests is too small and too risky to play a serious role as a climate change mitigation tool

My free online class on Coursera.org entitled Global Warming I: The Science and Modeling of Climate Change has already served 45,000 people (started, not finished) in the four times that it’s run. Now it’s set up in a new format, called “on demand mode”, which allows people to start, progress, and finish on their own calendars. This would be an advantage if a teacher wanted to use the material to supplement a class; a new cohort of learners is launched every month, so the next class start date is never more than a month away.

A new, supplemental class to the first one has been added and will come online on Monday, called Global Warming II: Create Your Own Models in Python or Fortran. This takes advantage of new code-grading machinery at Coursera to automatically run your code through its paces. There is also a peer code-review step, where you will get feedback on your commenting and variable-naming skills, and provide feedback to others. The class gives detailed instructions to create simple models of: time evolution of global temperature, the ice albedo feedback drop into snowball Earth, an ice sheet, and a shallow-water circulation model. The class is intended for people who are new to programming, or new to Python, or wish to enhance their understanding and appreciation of some cool science of Earth’s climate system.

The classes are supported by the same interactive on-line interactive climate system models as before, at http://climatemodels.uchicago.edu/, with some new additions, both of which generate animations of their time-dependent solutions.

One is a Hurricane simulator using a model from Kerry Emanuel, which can demonstrate the sensitivity of ocean temperature, ocean mixing, and atmospheric structure on hurricane evolution.

The other, the Permafrost model, is a simulation of a soil or sediment column in which ice and methane hydrate can form. The model shows how the brine salinity thermodynamically excludes methane hydrate from forming until you get to the base of the permafrost zone, and also how long it takes to warm a soil column by warming the surface. This model shows why I do not believe in an imminent methane climate catastrophe from Arctic Ocean methane hydrates.

Global Warming: The Science and Modeling of Climate Change is a free online adaptation of a college-level class for non-science majors at the University of Chicago (textbook, video lectures). The class includes 33 short exercises for playing with on-line models, 5 “number-cruncher” problems where you create simple models from scratch in a spreadsheet or programming language, and 8 “explainer” assignments where you explain some concept as you would to a smart 11-year old child (short, simple, clear), and exchange these with other students in the class for feedback. The discussion forums are very lively, as thousands of people from around the world make their way through the video lectures and exercises, lots to chat about. This is our third run of the class, so we’re getting the kinks out. We hope you find it useful. September 29 – December 31 2014.

methane_pie

XKCD, the brilliant and hilarious on-line comic, attempts to answer the question

How much CO₂ is contained in the world’s stock of bottled fizzy drinks? How much soda would be needed to bring atmospheric CO₂ back to preindustrial levels?

The answer is, enough to cover the Earth with 10 layers of soda cans. However, the comic misses a factor of about two, which would arise from the ocean. The oceans have been taking up carbon throughout the industrial era, as have some parts of the land surface biosphere. The ocean contains about half of the carbon we’ve ever released from fossil fuels. We’ve also cut down a lot of trees, which has been more-or-less compensated for by uptake into other parts of the land biosphere. So as a fraction of our total carbon footprint (fuels + trees) the oceans contain about a third.

At any rate, the oceans are acting as a CO₂ buffer, meaning that it’s absorbing CO₂ as it tries to limit the change to the atmospheric concentration. If we suddenly pulled atmospheric CO₂ back down to 280 ppm (by putting it all in cans of soda perhaps), the oceans would work in the opposite direction, to buffer our present-day higher concentration by giving up CO₂. The land biosphere is kind of a loose cannon in the carbon cycle, hard to predict what it will do.

Ten layers of soda cans covering the whole earth sounds like a lot. But most of a soda can is soda, rather than CO₂. Here’s another statistic: If the CO₂ in the atmosphere were to freeze out as dry ice depositing on the ground, the dry ice layer would only be about 7 millimeters thick. I guess cans of soda pop might not be the most efficient or economical means of CO₂ sequestration. For a better option, look to saline aquifers, which are porous geological formations containing salty water that no one would want to drink or irrigate with anyway. CO₂ at high pressure forms a liquid, then ultimately reacts with igneous rocks to form CaCO₃.

Further Reading

Tans, Pieter. An accounting of the observed increase in oceanic and atmospheric CO2 and
an outlook for the Future. Oceanography 22(4) 26-35, 2009

Carbon dioxide capture and storage IPCC Report, 2005