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Blogs by Pamela Harris
Global warming 11/16/2015 12:15:52 PM
BETWEEN 1998 and 2013, the Earth’s surface temperature rose at a rate of 0.04°C a decade, far slower than the 0.18°C increase in the 1990s. Meanwhile, emissions of carbon dioxide (which would be expected to push temperatures up) rose uninterruptedly. This pause in warming has raised doubts in the public mind about climate change. A few sceptics say flatly that global warming has stopped. Others argue that scientists’ understanding of the climate is so flawed that their judgments about it cannot be accepted with any confidence. A convincing explanation of the pause therefore matters both to a proper understanding of the climate and to the credibility of climate science—and papers published over the past few weeks do their best to provide one. Indeed, they do almost too good a job. If all were correct, the pause would now be explained twice over.
This is the opposite of what happened at first. As evidence piled up that temperatures were not rising much, some scientists dismissed it as a blip. The temperature, they pointed out, had fallen for much longer periods twice in the past century or so, in 1880-1910 and again in 1945-75 (see chart), even though the general trend was up. Variability is part of the climate system and a 15-year hiatus, they suggested, was not worth getting excited about.
NASA scientists have been keeping an eye on the movement of CO2 across land, air and sea in an effort to zero in on the changes in store for our planet.
CO2 concentrations in the atmosphere are the highest they’ve been in 400,000 years. Despite the commitments to try and rein in carbon pollution, there’s still little sign human emissions will slow anytime in the near future, let alone drop to zero.
That has the world on track to cross the symbolic atmospheric CO2 threshold of 400 parts per million (ppm) permanently this year or early next year. And it also means that the climate will continue to change leading to warmer temperatures, higher and more acidic oceans, and shifts in extreme weather.
Yet CO2 and corresponding impacts would be a lot higher if it weren’t for plants, like giant sequoias to microscopic plankton, that absorb about half of all human CO2 emissions in a given year. That’s why NASA is interested in monitoring the world’s greenery or what they’ve termed the “other half” of the carbon equation.
One of the most vigorously debated topics on Earth is the issue of climate change, and the National Environmental Satellite, Data, and Information Service (NESDIS) data centers are central to answering some of the most pressing global change questions that remain unresolved. The National Centers for Environmental Information contains the instrumental and paleoclimatic records that can precisely define the nature of climatic fluctuations at time scales of a century and longer. Among the diverse kinds of data platforms whose data contribute to NCEI's resources are: Ships, buoys, weather stations, weather balloons, satellites, radar and many climate proxy records such as tree rings and ice cores. The National Oceanographic Data Center contains the subsurface ocean data which reveal the ways that heat is distributed and redistributed over the planet. Knowing how these systems are changing and how they have changed in the past is crucial to understanding how they will change in the future. And, for climate information that extends from hundreds to thousands of years, paleoclimatology data, also available from the National Centers for Environmental Information, helps to provide longer term perspectives.
