The Complex Business of Measuring Climate Change

Have you ever wondered exactly how scientists track climate change and the warming of the world at a global level? Estimating the overall surface temperature of the Earth isn’t easy when you have to account for seasonal variations across six continents and four oceans. It requires compiling data from satellites positioned high up in the atmosphere and from hundreds of meteorological stations scattered across the globe. However being able to compare average global temperatures from year to year is incredibly important, and allows scientists to track the progress of climate change.

Fortunately leading scientific institutions make it their business to record as accurate a picture of global temperatures as possible, using sophisticated techniques that have grown more and more accurate over the years. This month what are probably the three most respected climate research centers in the world released their finings on how global temperatures from 2010 compared to other years. All three bodies—the US-based National Aeronautics and Space Administration (NASA) and National Oceanic and Atmospheric Administration (NOAA), and the UK-based Met Office—concluded 2010 was one of the top two warmest years since record-keeping began in 1880.

According to NASA, 2010 tied with 2005 for the title of warmest year ever. Before coming to this conclusion NASA scientists gathered information from over a thousand temperature data sites and looked at satellite records of ocean surface temperatures. This is the kind of comprehensive process needed to sort out merely local weather events from true global trends. The findings confirm climate change is still going on. Since the end of the 1970s, global temperatures have increased steadily at a rate of 0.36 degrees Fahrenheit per decade.

NOAA findings largely agree with those of NASA, and rank 2010 and 2005 as the two warmest years on record. The Met Office, using similar comprehensive data-gathering methods, has come to slightly different conclusions and ranks 2010 as the second warmest year behind 1998 (NASA awards 1998 a close second place behind 2010 and 2005). Considering the complexities involved in estimating the Earth’s temperature, some small discrepancies between the three leading research bodies are to be expected.

However NASA, NOAA, and the Met Office all agree on the most important thing: 2010 was one of the warmest years in recorded history, and recent decades have seen a steady warming trend caused by human activity. Climate change will continue unless quick action is taken to reduce carbon emissions. Meanwhile the amount of warming we’ve seen already has almost certainly contributed to an increase in weather-related disasters around the world. 2010 saw record floods, fires, and heat waves in many countries, and 2011 is already shaping up to be much the same.

Next time you’re with a global warming denier who looks out the window, sees snow outside, and declares the evidence for climate change a myth, you’ll be in a position to explain that the science of climate change is a little more complicated than that. As independently verified by three leading research bodies that have combed the Earth’s surface for data, the world is getting warmer even if variations in weather sometimes mask the trend at a local level. Modern science has allowed us to see more clearly than ever what climatologists have suspected for decades: human activity’s impact on the climate is real, measureable, and growing all the time.

Photo credit: NASA Goddard Space Flight Center