Satellites: Sea level rise to reach 2 feet by 2100

A new study in the Proceedings of the National Academy of Sciences confirms what global climate models have predicted. Melting ice sheets and Greenland and Antarctica combined with thermal expansion of warmer oceans is already pushing seas higher at a rate that will lead to at least 2 feet of sea level rise by 2100.

The study of satellite measurements shows the rate of sea level rise is accelerating over the past 25 years.

Here's one take on the PNAS study from Inside Climate News.

The rate of sea level rise is accelerating so fast that some coastal communities could confront an additional 4 inches per decade by the end of the century—a growing concern now confirmed by thorough measurements from space.

At that rapid pace of change, vulnerable communities might not be able to keep up. Storm surges will increase erosion and damage homes, businesses and transportation infrastructure in some areas. In other places, seawater will intrude on freshwater aquifers. In South Asia and the islands, people will lose the land where they live and farm. And the changes will arrive much faster than they do today.

Scientists have been warning about this speed-up for many years based on computer climate simulations. A new study released Monday confirms the modeled trend with a detailed analysis of satellite observations spanning a quarter of a century.

The findings, published in the Proceedings of the National Academy of Sciences, reinforce the outlook that average global sea level is likely to go up at least 2 feet by the end of this century compared to 2005 levels.

The study confirms that the Intergovernmental Panel on Climate Change(IPCC), NASA and the European Environmental Agency were correct when they found that the rate of change had increased in recent years.

And if the rate of acceleration intensifies—as it might if global warming speeds the melting of the Greenland and Antarctic ice sheets and glaciers—a 2-foot rise might be the low end of the likely range. The study assumes a steady acceleration at only the rate observed in the past 25 years.

Higher "base state"

The faster rate of sea levels rise will likely overwhelm adaptation efforts in many coastal cities by the end of this century. The higher base state of oceans means storm surge-driven coastal floods will deliver more severe damage.

We tend to think of sea level rise as a slow-motion steady event. The reality is sea level rise can be uneven over time and space. Sudden surges can occur as climate change-driven glacial melt water pulses into our oceans from ice sheets in Greenland and other locations. More severe climate change-enhanced storms like Hurricane Harvey then drive more damaging storm surges further inland due to the higher ocean base state. The increase in flooding and damage can be exponential, not linear.

It doesn't take a genius to see that the current rate of sea level rise is highly problematic in this century. Simply extrapolating out current trends over time yields some very unsettling future scenarios.

Some of the most impactful and costly climate change events over the next 80 years will likely be driven by higher sea levels and storm surges. Forced mass human migration of millions of people are more likely to cause widespread unrest. Significant economic shock waves from catastrophic storm events are increasingly likely to stress test insurance markets and other economic systems. Significant sections of major cities like Miami will be permanently or frequently underwater by 2100. Trillions of dollars in real estate are at increased risk.

Climate scientists and even the U.S. national security community have been warning about the impacts of rising sea levels for years. What's different about this week's study is the measured satellite data of what's already happening in our oceans. This is not some future model predicting what may happen. This is happening. Now.

Our oceans are rising faster than previously thought, and the pace is accelerating. Our atmosphere is warming and spawning more intense storms. My best assessment is we are just now at the beginning of an era of extreme climate change enhanced weather shocks like we saw last year with Hurricanes Harvey, Irma, and Maria.

This is the new normal.