Kevin Edward Trenberth (born 8 November 1944) is a New Zealand-American climate scientist who worked in the Climate Analysis Section at the US National Center for Atmospheric Research. In addition, his work is also highly cited by other scientists which is shown by his h-index of 136 (136 papers have over 136 citations) in 2023.

Trenberth received the 2017 Roger Revelle Medal and went on to study at the University of Canterbury, graduating BSc (Hons) with first-class honours in 1966.

After completing his studies at Canterbury, Trenberth worked at the Meteorological Service of New Zealand for two years, and was awarded a research fellowship in 1968 that allowed him to undertake doctoral studies at Massachusetts Institute of Technology. His ScD thesis, supervised by Edward Norton Lorenz and completed in 1972, was titled Dynamic coupling of the stratosphere with the troposphere and sudden stratospheric warmings.

Career

Trenberth returned to the Meteorological Service in Wellington, New Zealand, in 1972 after completing his PhD in the US. He worked there as a research scientist in the New Zealand Meteorological Service (1966–77).

Storms and hurricanes

Trenberth began some fundamental work related to changes in extremes with climate change in 1998. Until then, the focus of the scientific community had been mainly on changes in average temperatures and precipitation. Trenberth pointed out that the intermittent nature of precipitation mandated attention to intensity, frequency, duration, and type as well as amount. All storms reach out and gather in the available water vapor, which fuels the storm. Therefore, increases in water vapor in the atmosphere with higher temperatures will lead to greater intensity but less frequency of storms. This is because the total amount of water vapor is controlled by surface evaporation, not temperature. The prospects are therefore for more severe storms.

Until 2004, little attention had been paid to hurricanes and tropical storm changes, but the summer of 2004 was when four hurricanes made landfall in Florida. The question was whether there was a human global warming role in the activity and thus the damage. To Trenberth it was obvious that there was, and he spoke up when official NOAA statements on hurricanes attributed it all to natural climate variability. Trenberth participated in a tele-news conference, set up by Harvard University, and cautiously suggested that global warming was undoubtedly playing some role. This led to a major outcry from some hurricane meteorologists, and extensive criticism for example by Christopher Landsea, an American meteorologist.

As a response, Trenberth published further research on this topic in mid 2005.  Coincidentally, a record breaking hurricane season began shortly after (still in 2005) in which Hurricane Katrina caused all kinds of devastation in New Orleans. Two important studies who supported Kevin's research findings came out shortly thereafter: One by Kerry Emanuel, and another led by Peter Webster.  Further details on natural variability were provided in a publication by Kevin Trenberth and Dennis J. Shea in 2006. Trenberth further explained the concept to a broader audience in an article on hurricanes and climate change in Scientific American in 2007. It has the short and snappy title: "Warmer Oceans, Stronger Hurricanes".

Short-term climate variability

In a 2013 scientific paper in Geophysical Research Letters, Trenberth and co-authors presented an observation-based reanalysis of global ocean temperatures. This proposed that a recent hiatus in upper-ocean warming after 2004 had seen the long-term increase interrupted by sharp cooling events due to volcanic eruptions and El Niño. Despite this, ocean warming had continued below the 700m depth.

In a second 2013 paper, Trenberth and Fasullo discussed the effect of the 1999 change from a positive to negative phase of the Pacific Decadal Oscillation. This was associated with a change of surface winds over the Pacific which had caused ocean heat to penetrate below 700m depth and had contributed to the apparent global warming hiatus in surface temperatures during the previous decade.

In an interview, Trenberth said, "The planet is warming", but "the warmth just isn't being manifested at the surface." He said his research showed that there had been a significant increase in deep ocean absorption of heat, particularly after 1998. He told Nature that "The 1997 to '98 El Niño event was a trigger for the changes in the Pacific, and I think that's very probably the beginning of the hiatus". He said that, eventually, "it will switch back in the other direction."

Trenberth's explanation attracted wide attention in the press.

Hacked e-mail controversy in 2009

Kevin Trenberth was "one of the victims in 'Climategate' where hacked emails from climate scientists were distorted by climate-change deniers to sow confusion." In the Climatic Research Unit email controversy, an unlawfully disclosed email from Trenberth about one of his publications from 2009 was widely misrepresented; he had written, "The fact is that we can't account for the lack of warming at the moment and it is a travesty that we can't." In that 2009 paper, "An imperative for climate change planning: tracking Earth's global energy", Trenberth had discussed the distribution of heat and how it was affected by climate forcing, including greenhouse gas changes. This could be tracked from 1993 to 2003, but for the period from 2004 to 2008 it was not then possible to explain the relatively cool temperatures of 2008.

Trenberth has stated later: "It is amazing to see this particular quote lambasted so often. It stems from a paper I published this year bemoaning our inability to effectively monitor the energy flows associated with short-term climate variability. It is quite clear from the paper that I was not questioning the link between anthropogenic greenhouse gas emissions and warming, or even suggesting that recent temperatures are unusual in the context of short-term natural variability."

Public stance on climate change

For decades, Kevin Trenberth has been outspoken about climate change and the urgency to take action. One of his key messages has been: "It's real, the problem is cumulative, and we're causing it. Today's blanket of greenhouse gases would disperse only over centuries. Cutting emissions is the most important of all possible responses."

Trenberth received the 2017 Roger Revelle Medal from the American Geophysical Union for his work on climate change issues.

In January 2022 he was celebrated in a one-day Kevin Trenberth Symposium by the American Meteorological Society.

Publications

According to his staff page at NCAR: "Kevin Trenberth's total number of publications (as of November 2023) is 75 books or book chapters, 298 journal articles, 23 Technical Notes, 117 proceedings or preprints, and 87 other articles, plus four videos, for a total of 634 publications plus 4 videos, and many blogs and podcasts. On the Web of Science, there are 55,523 citations and an H index of 104 (104 publications have 104 or more citations). On Google Scholar, there are more than 132,000 citations and an H index of 136 (or 885 since 2018)." and New Zealand's Newsroom.

Selected books

  • 2023: Trenberth, K. E. (2023). A Personal Tale of the Development of Climate Science: The Life and Times of Kevin Trenberth , Auckland: Kevin E. Trenberth
  • 2022 : The Changing Flow of Energy Through the Climate System Cambridge University Press
  • 2000 : (in collaboration with K. A. Miller, L. O. Mearns and S. Rhodes) "Effects of Changing Climate on Weather and Human Activities" University Science Books / University Corporation for Atmospheric Research (UCAR)
  • 1993 : (editor) Climate System Modeling Cambridge University Press

See also

  • Earth's energy budget
  • Loop Current

References

  • Kevin E. Trenberth at the University Corporation for Atmospheric Research
  • "How to Fix the Climate-Change Panel", Questions for climate modeller and IPCC insider Kevin E. Trenberth, IEEE Spectrum, Oct. 2010.
  • "Check With Climate Scientists for Views on Climate", by Trenberth and 37 co-signers, Wall Street Journal, 1 February 2012
  • Article about Kevin Trenberth in University of Auckland magazine, August 2023