Human emissions of greenhouse gases such as carbon dioxide are causing the Earth to warm. We know this, and we have known about the heat-trapping nature of these gases for over 100 years. But scientists want to know how fast the Earth is warming and how much extra energy is being added to the climate because of human activities.

If you want to know about global warming and its future effects, you really need to answer these questions. Whether this year was hotter than last year or whether next year breaks a new record are merely one symptom of a warming world. Sure, we expect records to be broken, but they are not the most compelling evidence.

The most compelling evidence we have that global warming is happening is that we can measure how much extra heat comes in to the Earth’s climate system each year.

The most compelling evidence we have that global warming is happening is that we can measure how much extra heat comes in to the Earth’s climate system each year. Think of it like a bank account. Money comes in and money goes out each month. At the end of the month, do you have more funds than at the beginning? That is the global warming analogy. Each year, do we have more or less energy in the system compared to the prior year?

The answer to this question is clear, unassailable and unequivocal: the Earth is warming because the energy is increasing. We know this because the heat shows up in our measurements, mainly in the oceans. Indeed the oceans take up more than 92% of the extra heat. The rest goes into melting Arctic sea ice, land ice, and warming the land and atmosphere. Accordingly, to measure global warming, we have to measure ocean warming. Results for 2015 were recently published by Noaa and are available here.