Humans are changing Earth’s climate at an alarmingly fast rate
As climate scientist Wallace Broecker once said, “The climate system is an angry beast, and we are poking at it with sticks.” Photograph: Alamy |
Changes in atmospheric carbon dioxide and in the combined solar and carbon dioxide forcing over the past 420 million years. Illustration: Foster et al. (2017); Nature Communications. |
Over time, solar output has grown stronger, and atmospheric carbon dioxide levels have fallen due to an effect known as “weathering” of rocks and an increase in plant life. The authors of this study found that over the past 420 million years, the slow heating of the sun and slow decline of the greenhouse effect have roughly offset each other, leading to a fairly stable long-term global climate.
Changes in the solar and carbon dioxide forcings over the past 420 million years. Illustration: Foster et al. (2017); Nature Communications. |
The bottom frame in the chart shows the change in forcing (global energy imbalance) caused by the combination of changes in solar activity and the greenhouse effect. When the line is flat, the Earth’s energy balance is stable, and thus so is its climate. When there’s a steep change, something is upsetting that balance and causing a rapid climate change. The five colored lines toward the end of the chart show potential pathways we’ll follow, depending on how much fossil fuels humans burn over the coming decades.
It’s an alarming proposition. Climate deniers will often argue against taking action to curb carbon pollution because climate changed naturally in the past and carbon dioxide levels were higher in the past. One Republican congressman repeated these talking points in the latest House “Science” committee hearing. While both arguments are technically true, they miss several important points.
First, the rate at which we’re currently causing climate change is alarmingly fast – much faster than in most natural climate change events. Second, similar past rapid climate changes have caused mass extinction events. Third, the sun’s cooler past helped keep temperatures lower.
As renowned climate scientist Wallace Broecker once said, “The climate system is an angry beast, and we are poking at it with sticks.”
Denial101x lecture by Peter Jacobs.
As this new study shows, our poking sticks are getting bigger and bigger, and we’re poking the beast faster and faster. Meanwhile, climate deniers are egging us on because the beast has been angered in the past, and we’re not sure just how soon it will decide to maul us.
Links
- Future climate forcing potentially without precedent in the last 420 million years
- Earth is warming 50x faster than when it comes out of an ice age
- New study shows worrisome signs for Greenland ice
- New study links carbon pollution to extreme weather
- Inconceivable! The latest theatrical House 'Science' committee hearing
- Scientists understood the climate 150 years ago better than the EPA head today
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