Current Climate Models are Accurately Predicting Ocean and Global Warming within 3% of Observed Measurements Since 1992

As inhabitants of Earth, people should be concerned about the consequences of global warming and realizing its lasting effects on our only planet. Experts in tracking the rising issue, environmental scientists create models, quantitate temperatures in the atmosphere and ocean, and measure ocean levels, allowing us to understand how the world is experiencing an increased rate of heating since 1992.

Over the course of decades, scientists have made notable discoveries: 1) that more than 90% of the Earth’s warming in the last 50 years has occurred in the ocean and 2) that the rate of ocean warming has continued to accelerate the past three decades. Scientists published a paper in the Journal of Ocean Science and have presented an accurate model that is within 3% of global warming measurements since 1992.

The scientists presented, “a new estimate of ocean heating throughout its full depth [they measured temperatures at 3 different depth ranges in the ocean]. Second, a new technique to learn about ocean temperature changes in areas where there are few measurements and a large group of computer models to predict warming rates.” The scientists created an accurate model that was able to predict ocean temperatures, within 3%, since 1992. This creation allows scientists to analyze “what if scenarios” and enables them with better methods to know what will happen if nothing is done to improve Earth.

Scientists can determine the rate of global warming using a number of metrics including measuring the rate of energy increase in the Earth’s system. The three ways to identify the Earth’s energy are determining changes in ocean temperature, tracking the net flow of heat at the top of the atmosphere by using satellites, and measuring the rate of sea-level rise. Scientists believe that much of the sea level rise can be accounted for by the thermal (heat) expansion of water. The expansion of water and the increase in the sea level enable scientists to discern the global warming rate.

Scientists in this study, published in the Journal of Ocean Science, measured temperature changes in the ocean at different ocean depths: upper (0-700m), intermediate (700-2000m), deep (<2000m).

“Ocean heat content (OHC) is a vital climate indicator and is a key metric for global warming. How well ocean heating can be assessed by observations and can be simulated by climate models are a cornerstone of climate studies. By collecting the state-of-the-art observational ocean warming estimates and climate model results, this study gives the current status of our warming world and its future heating. We will continue to work hard to improve both measurements and models to better understand the climate change.” -Dr. Lijing Cheng

After collecting their measurements, the scientists were able to answer two critical questions: “how fast is the Earth warming?” and “how much will it warm further?”

The answer to the first: “According to the measurements, the Earth has gained 0.46 Watts per square meter between 1970 and 2005. Since, 1992 the rate is higher (0.75 Watts per square meter) and therefore shows an acceleration of the warming. To put this in perspective, this is the equivalent of 5,400,000,000,000 (or 5,400 billion) 60-watt light bulbs running continuously day and night.” –John Abraham

The answer to the second: “how did the models do? Amazingly well. From 1970 through 2005, the models on average showed a warming of 0.41 Watts per square meter and from 1992-2005 the models gave 0.77 Watts per meter squared. This means that since 1992, the models have been within 3 % of the measurements. In my mind, this agreement is the strongest vindication of the models ever found, and in fact, in our study we suggest that matches between climate models and ocean warming should be a major test of the models.” –John Abraham

Science is continuously improving upon prior results generated by their peers. When multiple studies reach the same conclusion, the results are robust and accurate. A paper published in 2015 reached similar conclusions. So did another paper published in 2016.

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In 2008, a group of climate experts, that included 20 climate modeling groups, met to collaborate to determine the best model for climate change. The scientists agreed on a new climate model built by expert climate scientists: the Coupled Model Intercomparison Project (CMIP5). Some scientists have estimated, using a CMIP5 model, that global average temperatures by 2050 will be warmer than any time in the past three million years. Climate change is real and is happening.

If we continue on our current trajectory and choose to take actions that continue to pollute our climate with greenhouse gases, the world will heat to unprecedented levels. We should leave this planet better than the way we found it.

 

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Cover image source: National Geographic

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