Evidence for Climate Change

Global surface average temperatures have been rising for decades. That’s beyond weather change, it’s climate change.  One of the difficulties of understanding the magnitude of climate change is that the differences we’ve seen so far are relatively small. What we see around us is weather. But weather is to climate like the changing surf is to the tide. Standing on the shore we see one wave higher than the next, but then several smaller and then another higher, and so on. Is the tide coming in or going out?

So with weather and climate. We see one hot year, then a cooler one, then another hot one and so on. Is the climate warming or not? To see the magnitude of climate change we need to look at the long term, not the short. And the long term trends are irrefutable. The climate is warming.

What is some key evidence for climate change?

See also an excellent compilation of evidence by the US National Academy of Science and the Royal Society.


Global Temperature is Rising

Compilations of land and ocean annual average surface temperatures, averaged across the globe, show a steady increase. The figure on the right shows average temperature change with zero taken as 1950.   The figure is an update of a figure from Hansen et al., 2010 . Some argue that climate change is stalled, based on the flat 5-year running […]

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Greenhouse Gases Increasing

Ice cores drilled from the thickest part of the eastern Antarctic ice sheet give us 800,000 years of data.  Carbon dioxide (CO2) and methane (CH4) levels in the atmosphere at the time of freezing of the ice can be measured.  Similarly the temperature at the time can be calculated.  This gives us a plot of […]

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Glaciers and Sea Ice Are Melting

Ice sheets, glaciers, and Arctic sea ice are melting at increasing rates.  This is important for two reasons.  First, ice tends to cool the planet, by reflecting back solar radiation and by absorbing heat energy as it melts.  White is more reflective than darker colors, like land or deep blue sea, which tend to absorb heat, as you know […]

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Animals and Crops Are Moving

Even small changes in temperature have important effects.  Not only do we see migration of animals and crops, we see significant loss of animals and plants to extinction. We see it with crops, such as stone-fruits, like plums and apricots, that are not getting enough chilling hours from Australia to California .   Sugar maples that are producing sugar farther […]

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