Anyone who thought we could turn back the climate clock and return to the old ‘normal’ is in for a disappointment. Even if we stop driving gasoline-fueled cars and having barbecues, no one alive today will ever experience that former normal again.
The sobering message comes from Bart Strengers, a climate scientist at the Netherlands Environmental Assessment Agency. “Due to the inertia of the climate system, it may take several decades, centuries, or even millennia before we can reverse the situation. Moreover, net-zero emissions are not enough; if we truly want cooling, negative emissions are necessary.”
But how did it come to this?
Roger Pielke Jr., an American expert on weather extremes, explains it in his blog ‘The Honest Broker’. Since 1950, heatwaves on our continent have been lengthening by 2.6 days every decade. And for every degree of global warming, extreme heat temperatures in Europe rise by 3.4 degrees.
Greenhouse gases from fossil fuel combustion (such as from diesel engines and central heating systems) reduce the infrared heat radiation emitted by the Earth into space. As a result, a significant amount of additional energy has accumulated in the climate system since 1971 – primarily in the oceans (89%), with 1% in the atmosphere.
Long-term effect
“More energy is available for any high-pressure system driven by warmer winds blowing over warmer seawater. And that means that – all other things being equal – standard meteorological conditions involving extreme heat are hotter than they used to be.”
The water balance is negative, and the soil is very dry, leading to increased heat and a risk of forest fires. Air pollution also contributes to heatwaves: polluting particles linger in the air and reflect sunlight.
Conversely, cleaner air allows more sunlight to pass through. And then there is the fact that highly paved, built-up environments retain heat for longer, resulting in warmer nights.
“There is little choice, then, but to tackle and avoid CO2 emissions,” says Pielke Jr. “But the effect will only be felt in the long term.” In short, it will get hotter before it gets cooler.
Unjustified inaction
The scale of inertia should in any case not be used to justify inaction. A recent study found that agreement with climate-delay arguments was associated especially strongly with lower support for environmental policies.
The fact is that we will not be able to reverse the warming already caused quickly, but we still exert considerable control over how much further warming occurs.
“Net zero is the brake, not the reverse gear. Negative emissions may eventually reverse part of the warming, while adaptation can reduce heat deaths, fire risks, and damage immediately,” Pielke Jr. concludes.
