• Skip to primary navigation
  • Skip to main content
  • Skip to primary sidebar
  • Skip to footer

RealClimate

Climate science from climate scientists...

  • Start here
  • Model-Observation Comparisons
  • Miscellaneous Climate Graphics
  • Surface temperature graphics

Blog – realclimate.org – All Posts

Does a slow AMOC increase the rate of global warming?

18 Jul 2018 by Stefan

Established understanding of the AMOC (sometimes popularly called Gulf Stream System) says that a weaker AMOC leads to a slightly cooler global mean surface temperature due to changes in ocean heat storage. But now, a new paper in Nature claims the opposite and even predicts a phase of rapid global warming. What’s the story?

By Stefan Rahmstorf and Michael Mann

In 1751, the captain of an English slave-trading ship made a historic discovery. While sailing at latitude 25°N in the subtropical North Atlantic Ocean, Captain Henry Ellis lowered a “bucket sea-gauge” down through the warm surface waters into the deep. By means of a long rope and a system of valves, water from various depths could be brought up to the deck, where its temperature was read from a built-in thermometer. To his surprise Captain Ellis found that the deep water was icy cold.

These were the first ever recorded temperature measurements of the deep ocean. And they revealed what is now known to be a fundamental feature of all the world oceans: deep water is always cold. The warm waters of the tropics and subtropics are confined to a thin layer at the surface; the heat of the sun does not slowly warm up the depths as might be expected. Ellis wrote:

“This experiment, which seem’d at first but mere food for curiosity, became in the interim very useful to us. By its means we supplied our cold bath, and cooled our wines or water at pleasure; which is vastly agreeable to us in this burning climate.”

[Read more…] about Does a slow AMOC increase the rate of global warming?

Filed Under: Arctic and Antarctic, Climate Science, El Nino, Hurricanes, Oceans

Model Independence Day

4 Jul 2018 by Gavin

We hold these truths to be self-evident, that all models are created equal, that they are endowed by their Creators with certain unalienable Rights, that among these are a DOI, Runability and Inclusion in the CMIP ensemble mean.

Well, not quite. But it is Independence Day in the US, and coincidentally there is a new discussion paper (Abramowitz et al) (direct link) posted on model independence just posted at Earth System Dynamics.

[Read more…] about Model Independence Day

References

  1. G. Abramowitz, N. Herger, E. Gutmann, D. Hammerling, R. Knutti, M. Leduc, R. Lorenz, R. Pincus, and G.A. Schmidt, "Model dependence in multi-model climate ensembles: weighting, sub-selection and out-of-sample testing", 2018. http://dx.doi.org/10.5194/esd-2018-51

Filed Under: Climate modelling, Climate Science, IPCC, statistics

Unforced Variations: July 2018

1 Jul 2018 by group

This month’s open thread for climate science related topics. The climate policy open thread is here.

Filed Under: Climate Science, Open thread

Forced Responses: Jul 2018

1 Jul 2018 by group

Open thread for climate policy and responses.

Filed Under: Climate Science, Open thread, Solutions

30 years after Hansen’s testimony

21 Jun 2018 by Gavin

“The greenhouse effect is here.”
– Jim Hansen, 23rd June 1988, Senate Testimony

The first transient climate projections using GCMs are 30 years old this year, and they have stood up remarkably well.

We’ve looked at the skill in the Hansen et al (1988) (pdf) simulations before (back in 2008), and we said at the time that the simulations were skillful and that differences from observations would be clearer with a decade or two’s more data. Well, another decade has passed!

[Read more…] about 30 years after Hansen’s testimony

References

  1. J. Hansen, I. Fung, A. Lacis, D. Rind, S. Lebedeff, R. Ruedy, G. Russell, and P. Stone, "Global climate changes as forecast by Goddard Institute for Space Studies three‐dimensional model", Journal of Geophysical Research: Atmospheres, vol. 93, pp. 9341-9364, 1988. http://dx.doi.org/10.1029/JD093iD08p09341

Filed Under: Climate modelling, Climate Science, Greenhouse gases

Will climate change bring benefits from reduced cold-related mortality? Insights from the latest epidemiological research

11 Jun 2018 by Stefan

Guest post by Veronika Huber

Climate skeptics sometimes like to claim that although global warming will lead to more deaths from heat, it will overall save lives due to fewer deaths from cold. But is this true? Epidemiological studies suggest the opposite.

Mortality statistics generally show a distinct seasonality. More people die in the colder winter months than in the warmer summer months. In European countries, for example, the difference between the average number of deaths in winter (December – March) and in the remaining months of the year is 10% to 30%. Only a proportion of these winter excess deaths are directly related to low ambient temperatures (rather than other seasonal factors). Yet, it is reasonable to suspect that fewer people will die from cold as winters are getting milder with climate change. On the other hand, excess mortality from heat may also be high, with, for example, up to 70,000 additional deaths attributed to the 2003 summer heat wave in Europe. So, will the expected reduction in cold-related mortality be large enough to compensate for the equally anticipated increase in heat-related mortality under climate change? [Read more…] about Will climate change bring benefits from reduced cold-related mortality? Insights from the latest epidemiological research

Filed Under: Climate impacts, Climate Science, statistics

Unforced variations: June 2018

2 Jun 2018 by group

This month’s open thread. We know people like to go off on tangents, but last month’s thread went too far. There aren’t many places to discuss climate science topics intelligently, so please stay focused on those.

Filed Under: Climate Science, Open thread

Does global warming make tropical cyclones stronger?

30 May 2018 by Stefan

By Stefan Rahmstorf, Kerry Emanuel, Mike Mann and Jim Kossin

Friday marks the official start of the Atlantic hurricane season, which will be watched with interest after last year’s season broke a number of records and e.g. devastated Puerto Rico’s power grid, causing serious problems that persist today. One of us (Mike) is part of a team that has issued a seasonal forecast (see Kozar et al 2012) calling for a roughly average season in terms of overall activity (10 +/- 3 named storms), with tropical Atlantic warmth constituting a favorable factor, but predicted El Nino conditions an unfavorable factor.  Meanwhile, the first named storm, Alberto, has gone ahead without waiting for the official start of the season.

In the long term, whether we will see fewer or more tropical cyclones in the Atlantic or in other basins as a consequence of anthropogenic climate change is still much-debated. There is a mounting consensus, however, that we will see more intense hurricanes. So let us revisit the question of whether global warming is leading to more intense tropical storms. Let’s take a step back and look at this issue globally, not just for the Atlantic. [Read more…] about Does global warming make tropical cyclones stronger?

Filed Under: Climate Science, Hurricanes, Oceans

If you doubt that the AMOC has weakened, read this

28 May 2018 by Stefan

A few weeks ago, we’ve argued in a paper in Nature that the Atlantic overturning circulation (sometimes popularly dubbed the Gulf Stream System) has weakened significantly since the late 19th Century, with most of the decline happening since the mid-20th Century. We have since received much praise for our study from colleagues around the world (thanks for that). But there were also some questions and criticisms in the media, so I’d like to present a forum here for discussing these questions and hope that others (particularly those with a different view) will weigh in in the comments section below. [Read more…] about If you doubt that the AMOC has weakened, read this

Filed Under: Climate modelling, Climate Science, Instrumental Record, IPCC, Oceans, Paleoclimate

Transparency in climate science

12 May 2018 by Gavin

Good thing? Of course.*

[Read more…] about Transparency in climate science

Filed Under: Climate modelling, Climate Science, Instrumental Record, Paleoclimate

  • « Go to Previous Page
  • Page 1
  • Interim pages omitted …
  • Page 26
  • Page 27
  • Page 28
  • Page 29
  • Page 30
  • Interim pages omitted …
  • Page 137
  • Go to Next Page »

Primary Sidebar

Search

Search for:

Email Notification

get new posts sent to you automatically (free)
Loading

Recent Posts

  • The most recent climate status
  • Unforced variations: May 2025
  • Unforced Variations: Apr 2025
  • WMO: Update on 2023/4 Anomalies
  • Andean glaciers have shrunk more than ever before in the entire Holocene
  • Climate change in Africa

Our Books

Book covers
This list of books since 2005 (in reverse chronological order) that we have been involved in, accompanied by the publisher’s official description, and some comments of independent reviewers of the work.
All Books >>

Recent Comments

  • Kevin McKinney on Unforced variations: May 2025
  • MA Rodger on The most recent climate status
  • Susan Anderson on Unforced variations: May 2025
  • Susan Anderson on Unforced variations: May 2025
  • patrick o twentyseven on Unforced variations: May 2025
  • patrick o twentyseven on Unforced variations: May 2025
  • jgnfld on The most recent climate status
  • jgnfld on The most recent climate status
  • James Charles on Unforced variations: May 2025
  • Thomas W Fuller on The most recent climate status
  • Socrates' Pet Scorpion on The most recent climate status
  • Socrates' Pet Scorpion on Unforced variations: May 2025
  • The Prieto Principle on The most recent climate status
  • The Prieto Principle on Unforced variations: May 2025
  • The Prieto Principle on The most recent climate status
  • Tomáš Kalisz on Unforced variations: May 2025
  • The Prieto Principle on Unforced variations: May 2025
  • The Prieto Principle on Unforced variations: May 2025
  • The Prieto Principle on Unforced variations: May 2025
  • Keith Woollard on The most recent climate status

Footer

ABOUT

  • About
  • Translations
  • Privacy Policy
  • Contact Page
  • Login

DATA AND GRAPHICS

  • Data Sources
  • Model-Observation Comparisons
  • Surface temperature graphics
  • Miscellaneous Climate Graphics

INDEX

  • Acronym index
  • Index
  • Archives
  • Contributors

Realclimate Stats

1,365 posts

11 pages

243,291 comments

Copyright © 2025 · RealClimate is a commentary site on climate science by working climate scientists for the interested public and journalists.