4 October 2016
Guest post by Erica Grow
Meteorologist at WNBC
New York City
It happened again. August 2016 was the warmest August on record across the globe. If that news sounds familiar to you, you’re not mistaken. It was, in fact, the sixteenth straight month of record-breaking temperatures, with global average temperature data dating back to 1880. The so-called “Super El Nino”, which lasted from late 2014 through the first half of this year, has ended. And still, the records continue to fall. 2016 is on pace to break the record for the hottest global average temperature ever measured, setting a new high water mark established in 2015. In fact, if current trends continue, this will be the third straight year setting a new record for global average temperature, with measurements from NASA and NOAA dating back to 1880.
Scientists are taught to look at everything with a critical eye. Theories are not proven and accepted until all the possible “what ifs” have been fully investigated, dissected, and analyzed for flaws. This exhaustive and thorough process has already taken place for the theory of human involvement in the current warming cycle our planet is undergoing. It is not a theory anymore; it’s a fact. This is why the most recent IPCC (Intergovernmental Panel on Climate Change) report used the strongest language yet to verify its findings, saying that “Human influence on the climate system is clear,” and “…many of the observed changes are unprecedented over decades to millennia”. Human activity is causing the global average temperature to rise at breakneck pace. And yet, there are enough dissenting voices present to create a real controversy. How is this possible? I think the complexity of the process of global warming, and the many strange ways this process manifests in our atmosphere, ocean, and cryosphere are to blame.
A critical element to understanding this process is gaining an understanding that global warming is not linear. We will not see the global average temperature rise at a steady, consistent pace. The world’s oceans, which cover about 70% of Earth’s surface, are a very efficient heat sink. Natural oscillations in our hydrosphere cause variances in the amount of heat the oceans pull from the air. These oscillations can last for decades at a time. Researchers have shown that this incredible capacity for the ocean to ingest heat from the air is likely responsible for the notorious “pause” in the rise of global temperatures that was observed from 1999 until 2013. (It’s worth noting that temperatures were still warmer than the 20th century average during this time.)
Oscillations are a natural and ever-present part of our climate, a fact that has raised suspicion as to whether our current warming is just a part of Earth’s natural ebb and flow. But a closer look shows that this is virtually impossible. Climatologists have created models that accurately replicate the temperature regime over the past 200 years, since the dawn of the Industrial Revolution. When the exact same models are run without including industrial emissions, the global average temperature actually drops as time goes on. This means that if it were not for human input, Earth would currently be in a cooling period, not warming.
By the way, the advances in climate modeling over the past couple generations are nothing short of remarkable. Our current weather models cannot produce results as accurate in a 10-day forecast for a single location than our climate models can create over centuries worth of data. This may be counterintuitive. How could a 200 year forecast be better than a 10 day forecast? The answer essentially lies with the difference between weather and climate. Imagine this difference being like a baseball team. Weather is like a player’s performance at the plate today, whereas climate is like his career batting average. It’s much easier to predict whether a particular player belongs in the cleanup position in your lineup than predicting if he will hit a home run today. The same holds true for weather.
We can much more accurately predict changes in the overall temperature regime than individual temperature records on a single day at a single location. While we do not know if that record high temperature that was reached yesterday didn’t happen, for instance, 1000 years ago, we do know what the overall climate was like 1000 years ago by studying sedimentary rock, air bubbles in glacial ice, and other geological record keepers.These climate proxies show us that temperatures are rising faster now than ever before in human history.
Global warming and our climate is sort of like a mosaic. Up close, there are pieces that don’t seem to fit the picture. Cherry-picked data, such as a periodic increase in sea ice in the Antarctic or inconsistent sea level rise in parts of the globe, are exploited as talking points to muddy the waters and inject doubt about the validity of the findings on climate change. But just as a mosaic’s image becomes clear when you step back, a full review of all available data shows a very clear picture of a warming climate, and a human influence on that warming. The only question that remains is how this change in our climate will impact us as we move forward.