Record cold! Ships trapped in Antarctic ice! Even so, we can say with high confidence that the globe is warming because of carbon dioxide from our fossil fuel burning.
While we are writing this, if you head toward the North Pole from the center of this huge blob of cold air, the temperature rises.
An unusual circulation pattern has shifted very cold air down toward Pennsylvania. But the Northern Hemisphere remains most of a degree Fahrenheit above the late-20th-century average, with great warmth in many places including north of Norway.
Meanwhile, down south, the ships trapped in the ice are really telling us about “weather,” but if you insist on a climate spin, they show warming.
Why? In 1987, an immense iceberg broke off the Ross Ice Shelf in Antarctica. A huge chunk got stuck on the seafloor for many years, then drifted along the coast, broke another huge iceberg off the Mertz Glacier and then lodged on another local seafloor high.
Normally, Antarctic wintertime winds blow down from the huge, high ice cap, freezing ocean water along the coast and then blowing this sea ice away, exposing more water to freeze.
But, with an iceberg blocking the sea-ice conveyor belt, some of the sea ice sat for years, slowly thickening through the Antarctic winters.
The emerging story is that some of this multi-year iceberg-blocked sea ice broke free, and swirling storm winds then packed it around the Antarctic ships.
This really is “weather” in the bizarre world of Antarctica. But the Antarctic is warming, and warming does contribute to the break-out of icebergs and of land-fast sea ice, so warming may have contributed slightly to these recent events.
Antarctic sea ice is not the first place to look for the influence of warming.
The extra moisture in the warming air around Antarctica contributes to more snowfall and rainfall that “float” on the saltier, warmer ocean water beneath and thus freeze more easily in the frigid winds from the continent, contributing to the observed slight increase in Antarctic sea ice.
And no, scientists are not hugely surprised by this. As early as 1992, some climate modeling did show a little growth of Antarctic sea ice from a little warming before shrinkage from more warming.
Modeling Antarctic sea ice remains difficult, but the models have consistently predicted that warming would shrink Arctic sea ice, which has occurred and continues at a pace that will produce ice-free Arctic summers in a few decades.
We can say with high confidence that the world is warming.
Thermometer records from the National Oceanic and Atmospheric Administration show this — as do NASA, the Berkeley Earth project (with some funding from fossil-fuel sources), the Hadley Centre in England and others. Thermometers far from cities show warming, and in the ground, the ocean, taken aloft on balloons and looking down from space.
Living things show warming, agreeing with snow and ice that care about temperature.
The degree or so of warming so far has not made record cold disappear, but the warming has confirmed our scientific understanding. And that scientific understanding shows that if we continue burning fossil fuels at an accelerating rate without building the sustainable alternatives that nature provides abundantly, we face future shortages of energy in a world that is much more difficult for us to live in.
But if we learn while we burn, the science shows that we can use our knowledge, together with what we care about and where we want to go, to build a bigger economy, more jobs, greater national security and a cleaner environment more consistent with the Golden Rule.
A financial adviser is almost certain to tell you that a one-day blip in the market is not the end of your retirement fund. A cold snap or a ship locked in the ice of Antarctica is not the end of global warming.
Science doesn’t tell you what to invest in or whom to vote for, but science does give you information you can use in planning for the future.
Today’s weather is not climate. We have high scientific confidence that the climate is warming because of us, and that this knowledge gives us power to make wise decisions about the future.
Richard Alley is Evan Pugh Professor of Geosciences at Penn State and a widely known expert on glaciers and climate change. David Pollard is a senior scientist in the Earth and Environmental Systems Institute in Penn State’s College of Earth and Mineral Sciences.