On May 15, the Wall Street Journal published a commentary by Fred Singer which argued that rising sea levels are unrelated to global warming, that they won’t be much of a problem, and that there’s little we can do about them. Singer, whose history of disingenuous attacks on science on behalf of the tobacco, fossil fuel and other industries goes back nearly 50 years, is wrong on all counts.
Singer acknowledges that “sea levels are in fact rising at an accelerating rate,” but then argues that “the cause of the trend is a puzzle.” Perhaps Singer is puzzled as to the causes, but science is crystal clear about this. Worse, we know that without strong policy to limit CO2 emissions, the rising water will continue to accelerate, inundating all the coastal cities of the world.
Fundamentally, there are three reasons why the ocean is rising at an accelerating rate
- Adding heat to things causes them to change temperature (1st Law of Thermodynamics)
- Seawater volume increases with temperature (thermal expansion)
- Adding a volume of water to the oceans from melting land ice causes them to increase in height (conservation of water)
All three of these principles (conservation of energy and mass, and the thermal expansion of water) are bedrock principles of physics which have been established for centuries and can easily be verified by direct observation.
The effect of CO2 on the absorption of radiation has been understood for 160 years.
The effect of rising CO2 on the energy budget of the Earth is directly measured in the laboratory, from towers, from balloons and aircraft, and from satellites. We measure precisely how much extra heat is absorbed globally by CO2 because of burning carbon, all the time. Adding heat to the world causes it to warm up, for precisely the same reason that adding heat to a pot of water on the stove causes the temperature of the water to increase.
When water warms up, it expands
The precise increase in seawater volume with temperature is easy to measure and extremely well known. Nearly all the resulting change in heat content (more than 90%) is in the oceans, where temperatures are measured at all depths by thousands of autonomous instruments floating at different depths. Oceanographers know the three-dimensional temperature and density of the oceans worldwide to amazing precision from these floating sensors. Since 1992, we have also tracked rising sea levels everywhere on Earth by measuring the height of the ocean from space using laser altimeters. The expansion of the warming seas measured by the floats is completely consistent with the rising surface of the water measured by the lasers.
As the world warms, ice sheets on land in Greenland and Antarctica are melting, adding water to the oceans.
Just as we directly measure the effect of CO2 on heat and the effect of that heat on ocean temperatures and sea level, we also have satellite measurements of the volume and mass of the great ice sheets. The height of the ice is measured by radar and the mass is measured by the gravitational pull of the ice itself. These data show precisely how much water from the ice sheets in both Greenland and Antarctica is added to the oceans each year. The total rise in sea level is completely consistent with the additions from land ice and ocean expansion, all of which are precisely measured all over the Earth and to the bottom of the oceans.
The reason that sea levels are rising faster and faster is because every bit of coal, oil, and gas we burn adds to the CO2 in the atmosphere, absorbing more of the Earth’s radiant heat, and contributing more to the thermal expansion of seawater and the loss of land ice. This is not a mystery. It’s extremely well understood and documented by millions of direct measurements.
Without strong policy, coastal cities will be inundated and abandoned
The oceans will continue to rise faster and faster unless the world implements very strong policy to quickly reduce and eventually eliminate the burning of fossil fuels. Depending on how quickly these policies are put in place, seas will rise between one and eight feet by 2100, according to a 2017 report from the federal government, released under the Trump Administration. Without strong policy, coastal cities in the US and around the world will be inundated and abandoned.
Rising oceans are but one devastating consequence of inexorable global warming caused by burning fossil fuels. Luckily, it’s not too late to prevent the damage to the world and our economy. Nearly all the world’s nations have agreed to limit warming by cutting emissions. Maybe somebody should tell Fred Singer.