Climate Changed

Have you ever wondered why we call the large ice-covered island west of Iceland by the name Greenland? History has it that Eric the Red, who visited from Iceland in 982 A.D. and later returned to colonize the island, called it Greenland to attract potential settlers to join him in the endeavor. Parts of the southwest side of Greenland were suitable for farming, and the colonists thrived (or at least survived) for several generations.

Why was the southwest side of Greenland suitable to colonize and farm? That part of the world experienced what researchers call the “Medieval Warm Period” from 900 A.D. or so until 1300 or perhaps even 1350 A.D. The climate was warmer during these years, warm enough to grow wine grapes as far north as England and warm enough to pasture cattle as part of the Norse farming enterprise in Greenland. However, then the climate changed.

The “Little Ice Age” brought colder temperatures to Greenland, Iceland, and Europe. It began in about 1350 or so and ended many years later. This made farming and food production difficult, and probably contributed to the collapse of the Norse colonies in southwest Greenland. But the climate changed, again, and gave us more or less what we have today. Except that today’s climate is not any more static than it was in 900, 1300, or 1700 A.D. Our climate is dynamic, and responds to many different influencing effects.

Some clarifying comments are in order: 

First, while climate may change globally in terms of factors such as average ocean surface temperatures, air temperatures, and weather patterns, climate also varies locally from one region to another. For example, one region might warm while another cools, and one area might become wetter while another experiences drought. In other words, global climate includes significant regional variability. If we want to talk about climate with respect to public policy or climate with respect to its implications for humans, we need to be clear about the terms we use in the discussion.

Second, global climate can change more quickly than we might think. We see this in evidence from tree rings and ice cap cores, among other things. However, since day to day, season to season, and year to year weather puts its stamp on whatever the global climate might be doing (and, in turn, climate influences weather), it is hard to point to a particular year and say, “Aha! The climate changed right then!” In other words, global climate includes significant temporal (over time) variability. Our level of understanding of this temporal variability and the effects that drive it calls for some humility as we discuss climate and its implications.

Clarifications aside, given that the climate has changed in the past, there is no reason to think that it will not change again, or that it isn’t changing now. For example, notice the blue lakes on top of the ice sheet in the photo above. This photo dates from 5 June 2019 rather than from the end of a warm summer. So, does it say anything about our climate, that those lakes of meltwater are there atop the ice sheet? Or do they only reflect year-to-year variability in the weather?

At this point you may wonder how much influence humans have on climate change. People and their activities have a lot of influence on our planet, but there are many other factors to consider. Simply put, human-caused effects include emissions into the atmosphere, land-use changes, energy use, and other factors. Natural effects include cloud cover, fluctuations in energy output from the sun, volcanic eruptions, and other factors. And reality is more complicated since natural effects influence human activities and at least some human activities influence what might otherwise be considered natural effects (e.g., atmospheric emissions influencing cloud formation). The problems are complex, and we are still learning.

Contrary to what many politicians and some scientists say, as long as researchers make new discoveries and serious questions go unanswered, the science is not really settled. (More about whether science is ever really settled in a future blog post.) However, history shows that our climate and its associated weather patterns have changed, and more than once. So, what should we do, other than ignore the political bluster? A few people suggest re-engineering the climate on a global scale, but that seems risky, rash, and perhaps downright scary. Others call for re-engineering the US economy, but without obvious regard for what the rest of the world might do. The US tried that kind of experiment during the Carter administration when we decided to stop reprocessing plutonium and hoped the rest of the world’s nuclear powers would follow suit. The others did not follow our example then, so why do we think they would truthfully follow a new example and re-engineer their domestic economies now? For that matter, how do we know that reworking our economy would make the right differences in terms of aggregate effects on climate, health, or human welfare?

Prudence suggests that we continue to investigate how the climate changes, why it varies from one region to another, and how to anticipate these changes so that we can adapt. In other words, we need research to understand our climate, its dynamics, and its effects. Prudence also suggests that we develop options to mitigate the effects of climate change. In other words, we need to develop innovations in engineering, agricultural, hydrology, and other fields to be able to adapt. Meanwhile, if anyone tells you that they have all the answers, please tune up your critical thinking skills and don’t hesitate to probe those answers for more information!