The last five years have been the hottest five years on record. And 2020 has an excellent shot at once again grabbing the top slot.

But to understand why cities in Germany continue to experience record temperatures, why ice is melting increasingly rapidly on the poles and why forests are burning in California and Australia, it is necessary to turn our attention to Hawaii.

For more than 60 years, the volcanic island in the middle of the Pacific Ocean is where scientists have gone to measure our planet's pulse. An atmospheric monitoring station on the northern slope of the Mauna Loa volcano, located at an altitude of 3,397 meters (11,145 feet) above sea level, has produced the longest uninterrupted data-stream on the concentration of CO₂ in our atmosphere. It was initiated by the U.S. climate researcher Charles Keeling.

Carbon dioxide is an extremely effective greenhouse gas. Just a couple of molecules of CO₂ among a million air particles is enough to heat up the atmosphere. For the emergence and development of life, this greenhouse effect is extremely important, ensuring as it does that our planet isn't just a giant ball of ice orbiting the sun. But by burning massive amounts of fossil fuels, we humans have thrown the atmosphere off kilter.

In 1959, Keeling measured 316 CO₂ molecules for every 1 million molecules in the air, a measurement known as "parts per million" and abbreviated as ppm. In May 2020, the Mauna Loa measurement came in at 417 ppm, almost a third more than the initial value measured.

But what does that number tell us? Scientists at the University of Southampton discovered that in the Pliocene, which stretched from 5.3 to 2.6 million years ago, the CO₂ content in the atmosphere was between 380 and 427 ppm.

In other words, if humanity's greenhouse gas emissions climb for just another five years, we will have attained the highest atmospheric concentration of CO₂ in over 3.3 million years. Back then, sea levels were around 20 meters higher than they are today. Giraffes lived in Europe, plants grew in Antarctica and Greenland was mostly free of ice.

If humanity was forced to deal with such massive shifts in climate, global upheavals would be the result: Vast areas of flooding, unprecedented numbers of refugees and massive food shortages.

Since the beginning of the industrial age, which got its start in Britain in the second half of the 18th century, humans have been burning an ever-increasing amount of fossil fuels to increase the production of food and goods and to improve mobility. We are responsible for the significant rise in temperature and it is up to us to fix the problem. It’s just that we haven't yet been able to make much headway.

Air on the Earth's surface has already increased by a global average of around 1 degree Celsius (1.8 degrees Fahrenheit) in the last 150 years, which has resulted in a shifting of our planet's climate zones.

What It Means for Germany and the World

The temperature increases aren't the same around the world. Here in Germany, for example, temperatures have risen much more strongly than the global average, according to Germany's National Meteorological Service (DWD). The current decade, from 2011 to 2020, has been around 1.9 degrees Celsius warmer than the period when temperature data was first recorded (1881 – 1910). Furthermore, nine of the warmest 10 years in Germany since 1881 have occurred since the year 2000.

The hotspot of global warming, though, is the Arctic. The northern polar region is heating up more than twice as quickly as the rest of the planet. That is also a function of the fact that there is less and less ice to reflect sunlight and the heat it brings, leaving behind the dark seawater of the Arctic Ocean, which absorbs more light and heat. It is a vicious cycle.

In the Paris Climate Agreement, countries around the globe agreed on a goal of limiting warming to significantly less than 2 degrees Celsius relative to pre-industrial levels. Even better, the deal notes, would be a rise of just 1.5 degrees Celsius. As mentioned above, however, temperatures have already risen by 1 degree.

The difference between 2 degrees and 1.5 degrees may not sound like much. But when it comes to the consequences for coral reefs around the world, for example, or for Arctic ice, the discrepancy is quite consequential.

Carbon dioxide isn't the only greenhouse gas responsible for heating up our atmosphere. Methane is also a culprit, a gas produced by livestock, rice farming and the production and transportation of fossil fuels. Nitrous oxide, which can get into the atmosphere by way of overfertilization, and certain fluorides, used for cooling or insulation, are also harmful to our climate.

Greenhouse gases remain in the atmosphere and affect our climate for quite some time. A molecule of CO₂ emitted by your car today, for example, will still be hanging around in the atmosphere 1,000 years from now.

What We Must Do

That's a very long time for CO₂ to remain in the atmosphere. But it is technically possible to capture and store carbon dioxide from the air using CO₂ capture plants, as pilot projects in Switzerland and Iceland have shown.

Studies have indicated, however, that capturing carbon dioxide from the air is not only inefficient, but also very expensive compared to other climate protection measures. There are also problems with a process known as "Bio-Energy with Carbon Capture and Storage," or BECCS for short.

The most important element in protecting our climate is thus a significant reduction in the amount of greenhouse gases we emit. According to the Climate Action Tracker, current steps that have been taken to reduce emissions will produce a 2.9-degree Celsius rise in average global temperatures by 2100. And even if all countries achieve the targets they set in the Paris Agreement, we will see a 2.7-degree rise. In other words, there’s a lot that still needs to be done.

Pledges have been made to do much more. China, by far the global leader in CO₂ emissions, has announced that reductions will begin in 2030 and that the country hopes to become climate neutral by 2060. Europe is also considering much stricter climate goals. The European Commission wants to increase its reduction target from 40 percent to 55 percent by 2030 – relative to the base year of 1990.

According to a new study, Germany would have to reduce its net CO₂ emissions to zero by 2035 to achieve the 1.5-degree target. That would mean a much more rapid development of renewable energies – wind turbines and solar facilities in addition to the emissions-free production of hydrogen, for use in powering planes and cars or to replace coal in steel-mill operations.

Increasing numbers of people no longer want to leave it entirely to the government to do something for the climate. There are plenty of sources offering tips on reducing your own, personal climate footprint, including the Carbon Calculator from the German Environment Agency . Still, many Germans don’t seem to know what the best methods are for lowering individual CO₂ output.

Not only that, a recent online survey found that respondents only planned to adopt an average of 1.6 of the measures listed above. And rather than resolving to only rely on reusable shopping bags, it would be vastly more effective to significantly reduce our consumption of meat. Or to install efficient insulation and heaters in our homes. There is absolutely no reason to wait on adopting such measures, especially given the government subsidies available. Renters, meanwhile, should speak to their landlords.

And flying? We should all be thinking twice about getting on a plane. Dirk Notz, of the Max Planck Institute for Meteorology in Hamburg, and his colleague Julienne Stroeve, of the National Snow and Ice Data Center in Boulder, have calculated that a flight from Frankfurt to San Francisco and back is responsible for the disappearance of five square meters of Arctic sea ice. Per passenger.

In other words, it might be best to skip a visit to Hawaii – to the place where Charles Keeling first started documenting the ways in which we are changing our atmosphere.