If you follow climate science or environmental news, you are no doubt aware of the fact that there are a lot of seemingly conflicting reports about how much the global average temperature has risen and is rising.
Scientists, even the vast majority who support the existence of climate change, can disagree on just how much temperatures have changed, or how much they’re going to change. And the difference is largely due to how they get their data.
Estimates of temperature change based on computer models are often more severe than those based on historical data, looking at temperatures from various points around the world throughout the last century and a half. The reason for that difference is that historical records are incomplete.
Any historian would tell you that no historical record is complete, but in many cases, we don’t know what’s missing there. But in the case of climate data, we now for sure that many of the gaps are from the Arctic.
The Arctic is warming faster than the rest of the Earth, but that’s hard to tell from historical data because there are long periods where those temperatures weren’t being measured. Different sources of data such as air temperatures versus water temperatures can yield different results. Water warms more slowly, so water temperatures do not reflect changing global temperatures as quickly.
This doesn’t mean that historical data isn’t useful. It still remains an important part of studying human effects on the world, but it is an incomplete part. Computer modeling can be used to try and fill in some of those gaps, and efforts to do that have found estimates of future temperature change that are more in line with purely computer-modeled systems.
Science is as much about what you don’t know as it is about what you do, and knowing now what we didn’t know can help us in the future.