Martin Kennedy and colleagues searched the Australian outback for clues to the transition out of Snowball Earth. The answer, as it turns out, was much closer to home.

Silicate weathering reactions remove carbon dioxide from the atmosphere and store it in carbonate minerals. During the high atmospheric carbon dioxide conditions of the Early Eocene Climatic Optimum, rates of chemical weathering, physical erosion and denudation in the western USA were equivalent to the highest recorded rates in the non-glacial Quaternary.

Fjords line mountainous continental margins where icesheets and glaciers once stood. A two-dimensional model simulation suggests that fjords can be eroded within one million years, primarily in response to topographic ice steering and erosion from ice discharge. Subsequent glaciers that form on these landscapes are smaller and exhibit greater responses to climate change.

Using projected boundary conditions for the end of the twenty-first century, the frequency of Atlantic tropical cyclones and hurricanes in a regional climate model of the Atlantic basin is reduced compared with observed boundary conditions at the end of the twentieth century. This is inconsistent with the idea that higher levels of atmospheric greenhouse gases will result in increased Atlantic hurricane activity.

The termination of the Marinoan glaciation 635 million years ago is one of the most spectacular climate change events ever recorded. Methane release from equatorial permafrost might have triggered this global meltdown.

What should we do about climate change? The question is an ethical one. Science, including the science of economics, can help discover the causes and effects of climate change. It can also help work out what we can do about climate change. But what we should do is an ethical question.