Nav: Home

A new study provides a solid evidence for global warming

March 13, 2017

Global warming is driven by the Earth's energy imbalance (EEI): our planet traps more and more heat due to continuous increasing greenhouse gases. From the energy perspective, the global warming is actually ocean warming, since ocean stores more than 90% of the trapped heat. Therefore, ocean heat content (OHC) change is a fundamental indicator of global warming, thus direct measurement of OHC will provide a direct evidence for climate change.

Reliable assessment of historical OHC change is a key task in climate studies. OHC time series provided by independent international groups show large discrepancies for long-term trend, intra-seasonal, inter-annual and decadal variability, because there are many challenges in estimating historical OHC change.

"Firstly, one of the major ocean subsurface observations (i.e. XBT) contains systematic bias." Said Dr. Lijing Cheng from the Institute of Atmospheric Physics, Chinese Academy of Science(IAP,CAS), also a lead author of a new study (Cheng et al. 2017) published in Science Advances, "Secondly, temperature observations at ocean subsurface are extremely sparse, especially before 2005, since they were mainly distributed along the major shipping routes in the Northern Hemisphere."

During the recent decade, a new type of sensing device has been deployed (the Argo float system), which significantly increases the coverage of ocean data. However, there are still more than 60% of the ocean grids without any observations (if the global ocean is divided into 1 degree and 1 month grids). So a gap-filling method is required to make a "guess" for the temperature change in the ocean grids without observations. This "guess" is based on the spatial and temporal covariance of ocean temperature changes. In another word, the ocean changes at two locations are not completely independent; instead, they are correlated under physical rules. The gap-filling method works to utilize the correlation to reconstruction the missed information. The choice of different gap-filling methods is the major error source in global OHC calculation.

The study led by IAP, CAS, collaborated with NCAR, NOAA, and University of St. Thomas, made a major step to estimate historical OHC change. The new study applied an advanced XBT bias correction method, which is recommended according to an XBT community paper published in 2016 in Bulletin of the American Meteorological Society. This ensures that the observation bias is minimized. The key step made by the new study is the application of an advanced gap-filling method and a careful evaluation on the results. It is highlighted that this study uses the knowledge of recent well-observed ocean states, but subsample it using the sparse distribution of observations in the more distant past to show that the method produces startling good results since late 1950s.

This new work allows a more accurate assessment of how much heat has accumulated in the ocean (and Earth) system. The inferred ocean energy accumulation is larger than previous estimates, such as from the last Intergovernmental Panel on Climate Change Fifth Report (IPCC-AR5) in 2013. But it is consistent with the direct observations of Earth's energy imbalance at top of atmospheresince late 1980s. This new look at OHC and EEI changes over time provides greater confidence than previously possible, and the data sets produced are a valuable resource for further climate change study.

Prof. Fan Wang, deputy director of Institute of Oceanography, Chinese Academy of Science, commented on the paper, "This study provided a new reconstruction on ocean subsurface temperature change since 1960 for 0-2000m depths, and assessed historical ocean energy budget more accurately. So it will be a valuable resource for future studies of oceanic variability and its climatic impacts on both regional and global scales".
-end-
Established in February of 1928 (then called Institute of Meteorology of Academia Sinica), the Institute of Atmospheric Physics (IAP) was the very first and foremost research center carrying meteorological research in modern China. Today IAP has become a comprehensive atmospheric research institution, covering all aspects of atmospheric sciences.

The orientation and mission of IAP includes to study and explore the new laws of physical, chemical, biological and human processes happening in the Earth's atmosphere and in the interactions between atmosphere and surrounding environment; provide advanced theories, methods and technologies regarding monitoring, forecast and control of weather, climate and environment; cultivate top talented persons in this discipline; and serve the sustainable economic and social development and national security.

http://english.iap.cas.cn/

Institute of Atmospheric Physics, Chinese Academy of Sciences

Related Climate Change Articles:

A CERN for climate change
In a Perspective article appearing in this week's Proceedings of the National Academy of Sciences, Tim Palmer (Oxford University), and Bjorn Stevens (Max Planck Society), critically reflect on the present state of Earth system modelling.
Fairy-wrens change breeding habits to cope with climate change
Warmer temperatures linked to climate change are having a big impact on the breeding habits of one of Australia's most recognisable bird species, according to researchers at The Australian National University (ANU).
Believing in climate change doesn't mean you are preparing for climate change, study finds
Notre Dame researchers found that although coastal homeowners may perceive a worsening of climate change-related hazards, these attitudes are largely unrelated to a homeowner's expectations of actual home damage.
Older forests resist change -- climate change, that is
Older forests in eastern North America are less vulnerable to climate change than younger forests, particularly for carbon storage, timber production, and biodiversity, new research finds.
Could climate change cause infertility?
A number of plant and animal species could find it increasingly difficult to reproduce if climate change worsens and global temperatures become more extreme -- a stark warning highlighted by new scientific research.
Predicting climate change
Thomas Crowther, ETH Zurich identifies long-disappeared forests available for restoration across the world.
Historical climate important for soil responses to future climate change
Researchers at Lund University in Sweden, in collaboration with colleagues from the University of Amsterdam, examined how 18 years of drought affect the billions of vital bacteria that are hidden in the soil beneath our feet.
Can forests save us from climate change?
Additional climate benefits through sustainable forest management will be modest and local rather than global.
From crystals to climate: 'Gold standard' timeline links flood basalts to climate change
Princeton geologists used tiny zircon crystals found in volcanic ash to rewrite the timeline for the eruptions of the Columbia River flood basalts, a series of massive lava flows that coincided with an ancient global warming period 16 million years ago.
Think pink for a better view of climate change
A new study says pink noise may be the key to separating out natural climate variability from climate change that is influenced by human activity.
More Climate Change News and Climate Change Current Events

Top Science Podcasts

We have hand picked the top science podcasts of 2019.
Now Playing: TED Radio Hour

Accessing Better Health
Essential health care is a right, not a privilege ... or is it? This hour, TED speakers explore how we can give everyone access to a healthier way of life, despite who you are or where you live. Guests include physician Raj Panjabi, former NYC health commissioner Mary Bassett, researcher Michael Hendryx, and neuroscientist Rachel Wurzman.
Now Playing: Science for the People

#544 Prosperity Without Growth
The societies we live in are organised around growth, objects, and driving forward a constantly expanding economy as benchmarks of success and prosperity. But this growing consumption at all costs is at odds with our understanding of what our planet can support. How do we lower the environmental impact of economic activity? How do we redefine success and prosperity separate from GDP, which politicians and governments have focused on for decades? We speak with ecological economist Tim Jackson, Professor of Sustainable Development at the University of Surrey, Director of the Centre for the Understanding of Sustainable Propserity, and author of...
Now Playing: Radiolab

An Announcement from Radiolab