Can we really predict climate change?

TEXAS A&M (US) — No matter what is being done now for or against the environment, the effects may not be known for 40 years or more.

A new study analyzes 150 years of climate data to determine past trends and annual temperature fluctuations and then uses the data to simulate possible temperature scenarios for the rest of this century.

Details are published in the October issue of the Annals of the Association of American Geographers.

Doug Sherman and Steven Quiring, professors in the College of Geosciences Department of Geography at Texas A&M University, based their calculations on historical temperature records from 1850—the earliest date for verifiable instrumental records—to 2008.

Using a 30-year moving window, they extracted the observed temperature trend and the variability about the trend for all 130 overlapping.

“As we moved past 2008, we relied on the Intergovernmental Panel on Climate Change’s (IPCC) emission scenarios to provide the temperature trend and the natural temperature variability was simulated based on the
historical temperature records,” Quiring notes.

Their approach, which provides 1,000 possible future temperature scenarios from 2008 to 2100 for four different emissions scenarios (namely A1B, A2, B2 and constant commitment), takes into account natural climate variations such as volcanic activity, solar output, and fluctuations in the ocean from
phenomenon like El Nino and the North Atlantic Oscillation.

“This method incorporates the natural variability or noise in climate data,” Quiring explains.

The results produced a detailed and empirically based view of how the climate could change.

Even though it is evident that the world is currently experiencing one of the fastest warming rates since the beginning of the observational record, the results suggest it will take a long time, in the human context, before a statistically significant difference can be seen between the different IPCC future temperature trends and the current trend because of the impact of natural climate variability.

“In the end,” Sherman says, “we found that even with an aggressive international effort to reduce the amount of greenhouse gases, it may be decades before we can see definitive results.”

The research has broad-range implications on international policy making and protocols, including initiatives like cap-and-trade, a program that provides financial incentives to companies that pollute less than others.

“There is something here for both sides of the ‘war against global warming,'” Sherman points out.

“Do we charge ahead with international agreements and policies, or do we do nothing? Do we save money for our grandchildren’s future or do we try to save the climate, not knowing if our efforts will have any effect?

“Unlike a true war,” he says, “we cannot anticipate victory. We have, at best, a stalemate.”

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