How can scientists claim to predict climate change over 50 or more years when they can’t even get next week’s weather forecast right?
They can’t tell us in detail. But forecasting climate change is more like forecasting the seasons than the weather. We know winters are cold and summers are warm. Always. And it’s like that with greenhouse gases. Physicists have known for 200 years that gases like carbon dioxide trap heat. These gases are accumulating in the atmosphere, thanks to our pollution. They will heat up the atmosphere just as certainly as the summer sun heats us.
But surely it’s the job of scientists to deal in irrefutable evidence rather than predictions?
Nothing is absolutely certain or irrefutable. We could be hit tomorrow by an asteroid or a mega-volcano that wipes out warming for centuries. But I’d say climate science is a good deal more reliable than most economic predictions, because it is based on natural laws rather than how markets behave.
Anyway, how can they be sure that the earth has warmed in the last few centuries?
It hasn’t. Evidence from tree rings, the pollen in the bottom of lakes, gas bubbles in ice cores and a lot else, all suggests strongly that it was warm 800 or 900 years ago; then cooler during the little ice age; then warmer again in the 19th century. All this was due to explainable natural cycles. But during the second half of the 20th century there was fast global warming for which there are no known natural explanations. Only the known physics of our soaring emissions of greenhouses gases can explain events.
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