Are the models “running too hot”?

Recent media headlines have again discussed the issue of whether climate models are overly sensitive to greenhouse gases. These headlines have misinterpreted a study by Millar et al. which was discussing carbon budgets to limit global temperature rise to 1.5°C above pre-industrial levels.

A recent study by Medhaug et al. analysed the issue of how the models have performed against recent observations at length and largely reconciled the issue. An overly simplistic comparison of simulated global temperatures and observations might suggest that the models were warming too much, but this would be wrong for a number of reasons. Continue reading Are the models “running too hot”?

Weathermen of Ben Nevis

For twenty years between 1883 and 1904, three intrepid weathermen lived at the top of Ben Nevis – the highest mountain in the UK – experiencing some of the worst weather the country has to offer.

Every hour, day and night, winter and summer, and whatever the weather, one of them would step outside and check the meteorological instruments, diligently recording the observations.

This was a uniquely Victorian-era endeavour. Science for the sake of science. Rather than exploring the world’s polar regions like some of their contemporaries, these Weathermen were exploring the atmosphere.

There was simply no other way of learning in detail about how the atmosphere changed with height without living at the top of a mountain. So that is what they did.

Continue reading Weathermen of Ben Nevis

Linking global temperature and Arctic sea ice changes

As the annual September sea ice minimum in the Arctic approaches, the usual questions arise about whether this year will set a new record for the extent or volume of ice left at the end of the summer. Although there was a new winter record low in 2017 it is looking unlikely that the summer will also set a record for extent, but there is still a month to go.

We understand that sea ice melt is erratic – we should not expect new records every year, but the overall trend is towards less and less ice. But, what about looking further ahead? And, can we understand sea ice variations during the historical period? Continue reading Linking global temperature and Arctic sea ice changes

Greenland reflections

Icebergs are much like clouds. They form all shapes and sizes, with a multitude of colours and textures. They are dynamic, constantly shifting, and drifting with the prevailing currents and winds. Some days there are lots and other days there are few.

The regions where icebergs form are some of the most awe-inspiring environments on the planet, but are undergoing rapid changes. Recently, I was fortunate enough to witness this up close on a kayaking trip, touring some fjords of southern Greenland. Continue reading Greenland reflections

Changing wet and dry seasons

The fickle nature of weather patterns is ultimately responsible for the where and when of tropical rainfall extremes which wreak damage on agriculture, infrastructure and people. Tropical cyclones, such as Enawo which battered Madagascar in March, can severely impact low-lying, highly populated regions through intense rainfall combined with strong winds and storm surges. Explosive thunderstorms operating at smaller spatial scales can generate flash flooding and may lead to devastating landslides in mountainous terrain. A sustained dearth of rainfall or multiple failed seasonal rains, as implicated in drought currently impacting Somalia, Kenya and Ethiopia, are also inextricably linked with evolving weather patterns, often driven by the slower heart-beat of the oceans as they pace out the internal rhythm of El Niño Southern Oscillation and its decadal counterparts. Continue reading Changing wet and dry seasons