For the Provocations series, in conjunction with UCI’s “Fire & Ice: The Shifting Narrative of Climate Change” conference.
Melting ice is the most direct and indisputable evidence that the climate is warming. Glaciers and ice sheets worldwide, pole to pole, are melting, rapidly, ahead of projections, in a widespread fashion, and in direct response to climate warming caused by humans. As a result of this melt, sea level is rising faster now than 50 years ago, and it will continue to rise faster in the future. The signal is strong and confirmed by multiple lines of evidence, it cannot be denied, especially as it becomes larger with time.
Climate change deniers often cast doubt or controversy about these facts, but the deeper problem is to make the public understand the consequences of this ice melt over the long term. Glaciers and ice sheets melt slowly at the beginning, then faster and faster, up to the point where their disappearance becomes unstoppable. And it takes an even much longer time to reform them.
In other words, we have to think about long term commitments when dealing with sea level rise and ice melt, and that is a challenge.
A common mistake about melting ice is to mix the fate of sea ice, which is frozen seawater afloat on the ocean, and glacier ice, which comes from snowfall accumulated on land, densifying into ice, which flows downhill when it is thick enough.
Sea ice has been receding dramatically in the Arctic as a result of many factors, all associated with climate warming and positive feedbacks. In the Antarctic, however, the sea ice cover has been growing very slowly. Climate deniers have used that observation as a line of evidence that climate warming is not real. In reality, the evolution of sea ice in the Antarctica is linked to climate warming, due to the changes in prevailing winds in the Antarctic.
But more importantly, even though sea ice is melting because of climate change, it does not raise or lower sea levels, because it is simply frozen seawater, seawater that changes state, as when ice melts in a glass. Whereas the videos we sometimes see of land ice “calving” or breaking off a piece of land ice and melting into the sea does raise sea levels because it is like tossing a new ice cube into the drink.
Another common misleading idea is to look at the polar regions on short time scales, on a yearly scale or on a scale involving several years. The climate signal is blurred under natural variability, for the same reason that you cannot identify climate change by looking at the day to day weather.
Climate is the planet’s weather averaged over a long time, not years, but decades, several decades. This fact confuses many people, because the natural variability is so much larger than the long term climate signal.
There is endless debate — occasionally even among scientists — about whether a few cold years in a row might indicate that the warming trend at the poles was not climate change but rather a natural hiccup. There is discussion when a glacier speed-up is followed one year by a slow down, or when Greenland melted a lot one year but the next year is cold and it isn’t melting that much. Maybe, some speculate, this was all exaggerated.
Exaggeration scares scientists more than conservatism. Scientists themselves like to stay prudent and to under-predict changes, rather than alarm people. This natural and indeed professional concern over creating fear has had an important effect on how the science of climate change has been communicated over the years to the public and the press.
Further, political and industrial attacks on scientists studying climate have created a sense that exaggeration — or even just an accurate and complete but frightening statement of fact — could be very dangerous to you, could threaten your grants, your job, your family, and your well-being as a citizen. Thus the reluctance in communities involved in studying and communicating issues related to climate change to come out and just say very frankly what’s happening.
Another problem with the impact of climate on ice is that we have not been there before. The climate has been stable for the past 10,000 years. We have never seen polar ice sheets collapse. There is no recorded account of that. The fear of seeing the polar regions fall apart reaches to the deep unknown of our subconscious. We have no idea what it looks like and how to recognize it. As a result, we tend to deny the possibility that it could happen.
Another common misconception about melting ice is that it is happening so far from us, in cold regions, that it cannot possibly affect us here, thousands of miles away. Yet, polar regions participate in the global climate, and melting land ice in polar regions raises sea level worldwide. Ironically, because of the way the Earth’s crust responds to the melting of ice at the poles, sea level rises faster far from the poles than it does near the poles.
Yes, the ice sheets are far away, but they are relevant to us, even crucial. At the local level, other factors enter into play, such as ocean warming which is affected by its own natural variability and ground motion, so sea level rise will not rise in northern Canada at the same rate as in Los Angeles, and it won’t be the same in San Francisco than it is in Orange County.
To satisfy their own financial needs, climate deniers try to gain time. But we do not have time to waste. There is no red button to stop the process of climate change. However drastic are our actions to reduce carbon emissions, it will take thirty to forty years to see any benefit. And 30 to 40 years from now, the melting of ice will be far larger than what we are experiencing today.
Humanity must confront its fears in a new way, in a manner different from anything we have been used to.
Scientists compare climate change to a hidden giant waking up, who without question is going to do terrible damage. We cannot see the giant. But he is coming for us.
We are used to getting scared of things we can see, touch, feel, experience directly. We are afraid of fire because we know what a flame feels like to our skin. But our imaginations can’t take in the colossal size of the trauma climate change will cause.
Thus, we must urgently listen to the measured and knowledgeable voice of science, and make a decision that we don’t want to go there, and that we must try to stop the giant of our destruction where he stands — or at least cut him off at the knees.
Eric Rignot, a glaciologist who has done world-renowned studies of the Greenland and Antarctic Ice Sheets, is Donald Bren Professor of Earth System Science at UCI’s School of Physical Sciences, and a Senior Research Scientist for NASA’s Jet Propulsion Laboratory. He is a member of the National Academy of Sciences.