Climate deniers are fond of pointing to the climate "pause" or "plateau"--a recent 10-year pause in the long-term trend of rising global air temperatures--as evidence that global warming is not happening and that the climate change issue is a hoax created by environmental extremists to halt the march of progress. A review of the climate field, however, explains most of this effect.
First, terminology. Global warming is the simplistic term used by many to refer to climate change. It is true that average global air temps are rising and will continue to rise--on average and over the long term. But climate change effects are not equally distributed in time and space. Climate science actually says that despite overall average increases in air temps, local weather will become more variable and more extreme. So we will see hotter--and colder--weather in various places at various times.
This is already happening in the northern temperate latitudes, including most of the USA. As arctic sea ice melts, its coverage of the polar regions varies more from summer to winter and from one side of the region to another. This contributes to a breakdown in the formerly-solid high pressure area that used to sit over the north pole, and that used to regulate the flow of circumpolar winds and weather systems, otherwise known as the jet stream. The jet stream used to have a nice, even sine-wave shape, and produced alternating hot and cold, wet and dry weather patterns with some predictability. With the breakdown of the polar ice cap, however, the jet stream has become more irregular, loopier, slower, with the effect of making temperate-zone weather less predictable. So lately we get extended heat, or extended cold, or extended wet or dry periods, with less predictablity. That's the core paradox about climate change--it's not uniform hotter temperatures, it's increased unpredictability. And it's that unpredictability that is stressing agricultural, forests, species adaptation, etc.
Now back to the "pause." The recent plateau in air temps is explained by a few factors: one is the role of the oceans in regulating heat flow in the climate system. Oceans take up huge amounts of heat from the atmosphere, and recent analysis indicates that's been happening recently. However, that heat will find its way back into the atmosphere over time, so the plateau is only temporary. Second, for the last 25 years nations have been reducing emissions of chlorofluorcarbons (CFCs, mostly found in refrigeration systems as coolants) under the Montreal Protocol, which was signed in 1987 to address the stratospheric ozone problem (remember the "ozone hole?"). But CFCs are also very potent greenhouse gases, much more potent than CO2, and so reductions in CFC emissions have contributed to reductions in their associate greenhouse effect. Finally, changes in Asian rice cultivation methods have cut emissions of methane, which is 20+ times more potent than CO2.
So the temporary "pause" tells us several things: (1) it's NOT proof that climate change is a hoax, (2) changes in human activity such as CFC phaseout and agricultural methods can help solve the problem, and (3) deniers can't use spot data like cold snaps or freak snowstorms to deny climate change, because such events are in fact entirely consistent with climate science. Let's keep our eyes on the prize, and keep working on the solutions that we know are effective--cutting emissions of CFCs and then their successors HFCs, reducing methane emissions via agricultural and forestry practices, reducing black carbon (soot) pollution using proven methods, using energy efficiency as the economically-sound "first fuel" to limit growth in CO2 emissions, and then driving clean energy on the supply side to drive down emissions. We can do this!
First, terminology. Global warming is the simplistic term used by many to refer to climate change. It is true that average global air temps are rising and will continue to rise--on average and over the long term. But climate change effects are not equally distributed in time and space. Climate science actually says that despite overall average increases in air temps, local weather will become more variable and more extreme. So we will see hotter--and colder--weather in various places at various times.
This is already happening in the northern temperate latitudes, including most of the USA. As arctic sea ice melts, its coverage of the polar regions varies more from summer to winter and from one side of the region to another. This contributes to a breakdown in the formerly-solid high pressure area that used to sit over the north pole, and that used to regulate the flow of circumpolar winds and weather systems, otherwise known as the jet stream. The jet stream used to have a nice, even sine-wave shape, and produced alternating hot and cold, wet and dry weather patterns with some predictability. With the breakdown of the polar ice cap, however, the jet stream has become more irregular, loopier, slower, with the effect of making temperate-zone weather less predictable. So lately we get extended heat, or extended cold, or extended wet or dry periods, with less predictablity. That's the core paradox about climate change--it's not uniform hotter temperatures, it's increased unpredictability. And it's that unpredictability that is stressing agricultural, forests, species adaptation, etc.
Now back to the "pause." The recent plateau in air temps is explained by a few factors: one is the role of the oceans in regulating heat flow in the climate system. Oceans take up huge amounts of heat from the atmosphere, and recent analysis indicates that's been happening recently. However, that heat will find its way back into the atmosphere over time, so the plateau is only temporary. Second, for the last 25 years nations have been reducing emissions of chlorofluorcarbons (CFCs, mostly found in refrigeration systems as coolants) under the Montreal Protocol, which was signed in 1987 to address the stratospheric ozone problem (remember the "ozone hole?"). But CFCs are also very potent greenhouse gases, much more potent than CO2, and so reductions in CFC emissions have contributed to reductions in their associate greenhouse effect. Finally, changes in Asian rice cultivation methods have cut emissions of methane, which is 20+ times more potent than CO2.
So the temporary "pause" tells us several things: (1) it's NOT proof that climate change is a hoax, (2) changes in human activity such as CFC phaseout and agricultural methods can help solve the problem, and (3) deniers can't use spot data like cold snaps or freak snowstorms to deny climate change, because such events are in fact entirely consistent with climate science. Let's keep our eyes on the prize, and keep working on the solutions that we know are effective--cutting emissions of CFCs and then their successors HFCs, reducing methane emissions via agricultural and forestry practices, reducing black carbon (soot) pollution using proven methods, using energy efficiency as the economically-sound "first fuel" to limit growth in CO2 emissions, and then driving clean energy on the supply side to drive down emissions. We can do this!
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