1.1 How can we be so sure that the Earth is heating?

“Join the dots. It's happening. It's happening in your world, it's happening in my world. And let's be very clear about this - it is going to get much worse.” Dr Sunita Narain, Director General of The Centre for Science and Environment/

Independent temperature records from multiple official sources confirm that there is absolutely no doubt whatsoever that the Earth is heating. A graph showing global temperature change in the last 2019 years image source

Each of the last three decades has been successively hotter than the one before, 19 of the top 20 hottest years have occurred in the last 19 years, and the past four years have been the hottest on record. 2016 was the hottest year ever recorded, whilst in 2019, nearly 400 temperature records were broken across 29 countries, June 2019 was the hottest on record, and July 2019 was the hottest month ever recorded. As of July 2020, January 2020 was the warmest January ever recorded in Europe, we saw the hottest May ever and we already have an 85% chance that 2020 will turn out to be the hottest year on record.

Some people argue that global heating can’t be happening because the weather seems to be getting colder where they live. This may indeed be true, but what’s important to remember is that when we talk about global heating and climate change, we are talking about changes in long-term average trends in atmospheric conditions - normally measured over decades - whereas when we talk about the weather we are referring to short-term and local variability around that average.

What this means is, whilst we are clearly seeing an overall increase in average global temperatures, there can still be significant regional and yearly variations in the weather. In any one year there may be some parts of the world that are colder than usual, and there may be entire years that are colder than previous years. Indeed, those wishing to confuse the public that global heating isn’t occurring sometimes do so by pointing to misleading graphs that are based on false or misinterpreted data that refers to regional as opposed to global changes, or cherry-pick data that focus on short-term trends rather than looking at the bigger picture.

Land and Ocean Temperature Departure from Average Jan-Dec 2019 image source

An animation of how realists and contrarians view global warming - showing how curves are smoothed to show a trend image source

The key point is that long-term and global trends show unequivocally that our planet is not only heating up, but that its rate of heating is accelerating. In fact, it has even been proposed that it is climate change itself that is causing some regions to experience more extreme, colder winters due to the disruption to weather patterns.

Show your Stripes - global temperature change shown as colours 1850-2019 image source

It’s also worth noting that there is variation in how fast the climate is changing in different parts of the world. For example continental regions (where most people live) heat up much faster than the oceans. An extreme example of this is the Arctic, which is warming at more than twice the rate of the global average due to a phenomenon called Arctic Amplification. In contrast, there are areas of the globe that are warming a bit slower than the average.