Paleoclimate evidence on rapidity of climate change

How rapidly will climate change occur? Traditionally, the changes were expected to be linear -- that as the amount of carbon in the atmosphere went up, the temperature would rise proportionately. Over the past few decades, this view has increasingly been replaced with the recognition of tipping points and the possibility of comparatively rapid change. James Hansen and Makiko Sato have recently produced a pair of papers -- one technical and the other focused on a more general audience -- describing their recent findings suggesting that the bulk of change from certain feedback processes will occur in a period of decades rather than centuries. Here is the introduction from the non-technical version: Earth's Climate History: Implications for Tomorrow

The past is the key to the future. Contrary to popular belief, climate models are not the principal basis for assessing human-made climate effects. Our most precise knowledge comes from Earth's paleoclimate, its ancient climate, and how it responded to past changes of climate forcings, including atmospheric composition. Our second essential source of information is provided by global observations today, especially satellite observations, which reveal how the climate system is responding to rapid human-made changes of atmospheric composition, especially atmospheric carbon dioxide (CO2). Models help us interpret past and present climate changes, and, in so far as they succeed in simulating past changes, they provide a tool to help evaluate the impacts of alternative policies that affect climate.

Paleoclimate data yield our best assessment of climate sensitivity, which is the eventual global temperature change in response to a specified climate forcing. A climate forcing is an imposed change of Earth's energy balance, as may be caused, for example, by a change of the sun's brightness or a human-made change of atmospheric CO2. For convenience scientists often consider a standard forcing, doubled atmospheric CO2, because that is a level of forcing that humans will impose this century if fossil fuel use continues unabated.

We show from paleoclimate data that the eventual global warming due to doubled CO2 will be about 3°C (5.4°F) when only so-called fast feedbacks have responded to the forcing. Fast feedbacks are changes of quantities such as atmospheric water vapor and clouds, which change as climate changes, thus amplifying or diminishing climate change. Fast feedbacks come into play as global temperature changes, so their full effect is delayed several centuries by the thermal inertia of the ocean, which slows full climate response. However, about half of the fast-feedback climate response is expected to occur within a few decades. Climate response time is one of the important 'details' that climate models help to elucidate.

For those who want the technical details, here is the abstract of the scientific publication.

Paleoclimate data help us assess climate sensitivity and potential human-made climate effects. We conclude that Earth in the warmest interglacial periods of the past million years was less than 1{\deg}C warmer than in the Holocene. Polar warmth in these interglacials and in the Pliocene does not imply that a substantial cushion remains between today's climate and dangerous warming, but rather that Earth is poised to experience strong amplifying polar feedbacks in response to moderate global warming. Thus goals to limit human-made warming to 2{\deg}C are not sufficient - they are prescriptions for disaster. Ice sheet disintegration is nonlinear, spurred by amplifying feedbacks. We suggest that ice sheet mass loss, if warming continues unabated, will be characterized better by a doubling time for mass loss rate than by a linear trend. Satellite gravity data, though too brief to be conclusive, are consistent with a doubling time of 10 years or less, implying the possibility of multi-meter sea level rise this century. Observed accelerating ice sheet mass loss supports our conclusion that Earth's temperature now exceeds the mean Holocene value. Rapid reduction of fossil fuel emissions is required for humanity to succeed in preserving a planet resembling the one on which civilization developed.

Climate Change-Peak Oil Feedback Loops

From The Harbinger:

Mike Flannigan, a University of Alberta wildland fire professor and Canadian Forest Service researcher, told the Globe & Mail that climate change was one of the causes of the forest fire that burned down 485 homes and businesses in Slave Lake, Alberta Canada. “I think it’s consistent with what we expect from climate change. We’ve already seen increases in fire activity in Canada,” he said. The boreal forests are warming and drying out; lightening strikes start 35% of fires; and the pine bark beetle is attacking and killing the weakened trees, making them more vulnerable to fire. Thus far in 2011, 264,000 hectares of forest have burned in Alberta, three times the 2010 total.

A further consequence of climate change is, paradoxically, that the forest fires caused the shut down of oil production from the tar sands, Canada's chief source of carbon emissions and climate change. The Globe & Mail reports that "nearly 150,000 barrels of oil-equivalent production has been halted amid a massive string of blazes in the oil patch that has threatened some energy infrastructure and created major logistical hurdles for many crude operators. . . With roughly 150,000 barrels of shuttered crude production, Alberta companies are losing more than $10-million per day in revenue. . . For Alberta, that translates into roughly $1.7-million per day in lost royalties, a tally that adds to the significant blow already faced by a province that has committed $50-million toward massive rebuilding costs after the fires."

And again, paradoxically, climate change has also caused a reduction in the demand for gasoline in the United States, Canada's chief importer of tar sands oil. Massive flooding of the Mississippi River has actually shut down parts of the highway system and forced people to cut back on their driving.

Fadel Gheit, a senior oil analyst at Oppenheimer & Co. Inc, sites three causes of the US drop in demand for gasoline:

"First, the price of gasoline has stretched above the psychological breaking point for American drivers – hovering around $4 (U.S.) per gallon – prompting motorists to leave the car keys at home. Second, several major centres are suffering from massive floods, making highways impassable, again hampering driving habits. States in the Mississippi River Delta are staring down the threat of record floods as water spills over the banks of powerful rivers, with some Interstates closed and cities under water. Southeastern Missouri and southern Illinois have also been hit, and earlier this spring parts of northern states including Minnesota and North Dakota were under water. Third, a soft economy is once again hurting oil demand, Mr. Gheit said."

This is an unexpected confluence of the twin crises of climate change and peak oil: oil production is causing climate change, which is in turn creating climate conditions that are shutting down the production and consumption of oil. It is an ecological feedback loop of global proportions that has become directly observable.

The Price of Oil: Not as Simple as You Think

The Oil Drum has an article by George Mobus, an Associate Professor of Computing and Software Systems at the University of Washington, Tacoma: Peak Oil: How Supply Crunch Can Lead to Lower Prices (for a while!)

His model of the price of oil proposes models of the production, consumption and price of oil over multiple time scales and including multiple feed-back loops. In short, his model explains the non-linearity of the oil market, which mimics similar cycles in biological systems (aka, Panarchy, although he doesn't call it that). His model explains how oil prices fluctuate and, at short time scales, don't necessarily reflect current or future supply, although in longer time scales, the price of oil is generally trending upwards. The full model is represented below: