Latest news with #JournalofClimate
Newsroom
03-05-2025
- Science
- Newsroom
NZ oceanic ecosystems subject to biggest climate changes
Analysis: We need to talk about the weather and climate, again. As I and some fellow climate scientists have discovered, in research published in the Journal of Climate, the warming of the world's oceans is proceeding at different paces in different latitude bands and New Zealand is in a region where some of the biggest changes are occurring in the global ocean. This affects the atmospheric winds and weather patterns, which in turn change ocean currents and where the heat piles up in the ocean. Often warmer waters can influence the locations of fish and the health of marine ecology (such as kelp farms and phytoplankton). This will affect our local oceanic ecosystems. Our research involved producing maps and graphs of changes in incoming solar radiation at the top-of-atmosphere, and outgoing infrared radiation to space beginning in March 2000. We have also computed all changes in pressure, winds, temperatures, and humidity at all points in the atmosphere hourly, from 2000 to 2023. This meant we could compute the movement of atmospheric energy – heat, kinetic energy, potential energy, latent energy (moisture) – and changes over time. We also processed ocean observations after 1958 (the International Geophysical Year) when adequate data became available to map heat changes in the ocean down to a depth of 2km. Change from human activities is often called global warming because the main human influence is from changes in the atmospheric composition through the burning of fossil fuels that dump carbon dioxide, a greenhouse gas, into the atmosphere. That is, it traps heat that would normally be lost back to space and therefore increases temperatures at the surface. Moreover, carbon dioxide has a very long lifetime, even as it is recycled through photosynthesis in plants, and quickly becomes globally distributed. Carbon dioxide has increased since the 1800s by over half, and the rate of increase has been greatest in the last five years. It would be more accurate to call it global heating rather than warming. About 70 percent of the planet is ocean and, unlike the land, it soaks up heat. Heat slowly penetrates down and can now be tracked to well below depths of 2km. Surface hot spots or marine heat waves in the ocean are not uncommon and arise from favourable weather (light winds, sunny), but are now becoming pervasive. Our new study shows that these are changing weather patterns, and the sea level is rising by over 4mm a year. Warming oceans Our new research has uncovered rather distinctive patterns of change and why they are occurring. The changes over the last 25 years in the ocean relate strongly to the normal distribution of mid-latitude westerlies and tropical easterly trade-winds. Together these push waters to pile up from 30° to 50° latitude over the oceans (see graph below). Global mean Ocean Heat Content for 0-2000m relative to a base period 1981-2010, in ZettaJoules. The 95 percent confidence intervals are shown. Right: Trend from 2000-2023 in OHC for 0-2000m in W m-2. The ringed regions highlight the biggest increases. The greatest heating is near 40°N for northern oceans, and 40° to 45°S over the southern hemisphere – the latitudes of New Zealand. In turn the change in sea temperatures alters the atmosphere. Hence the atmosphere and ocean currents are systematically redistributing heat from global warming, profoundly affecting local climates. Our study shows the jet streams and associated storm tracks over the oceans in both hemispheres have shifted polewards. It never rains but it pours The atmosphere (the mixture of gases around the Earth) can hold about 7 percent more moisture for every 1C increase in temperature. Most moisture naturally occurs where temperatures are higher: near the surface, in the tropics and subtropics, and where surface waters (sea, lakes, etc) provide ample sources of moisture. The first order effect of the warmer ocean is greater evaporation of moisture, increasing atmospheric humidity. Global observations reveal over 7 percent increases in total column water vapour in the atmosphere since 2000. The increased moisture is then caught up in weather systems and so it rains harder than it otherwise would have. This is also likely to intensify a storm through the release of the latent heat that went into the evaporation in the first place. The result is more extreme atmospheric rivers and weather, and increased risk of flooding, as scientists are observing and the whole world is experiencing. Heating generally produces increased surface drying as water is sucked up into the thirsty atmosphere, and where it is not raining it leads to drought, heat waves and wildfires. Whether wildfires are a consequence depends on how well forests and other areas are managed. But atmospheric moisture and clouds are carried around by winds and get caught up in storms, including hurricanes/cyclones and atmospheric rivers. This can result in flooding rains, as happened in Auckland on January 27 2023 (over 280mm of rain in a day), and Cyclone Gabrielle in mid-February (widespread flooding and erosion in eastern North Island). Whether heavy rains result in flooding depends, of course, on drainage systems and surface water management, and whether people have settled in flood plains, which is so often the case as populations have exploded. The influence of La Niña in 2025 has meant extra rains for Australia, such as Cyclone Alfred in March 2025 that brought widespread flooding near Brisbane. As warm waters developed around New Zealand in February and March 2025, we experienced long dry spells and great holiday weather. But it catches up sooner or later, with strong damaging winds and heavy rains from Ex-Cyclone Tam April 16-19. The changes in winds have been shown to be in large part caused by changes in the atmospheric composition. There is a lot of speculation about changes in aerosols (pollution) and related changes in cloud, especially from clean-up of use of high-sulphur coal by ships in the North Atlantic and cleaner air from China, but these effects are not in play in the southern hemisphere. Rather the warming oceans and changes in atmospheric circulation are altering the ways the climate system works, with consequences for where storms and rains occur, and hence risk of flooding and erosion. Atmospheric heatwaves and marine heatwaves in and around New Zealand have increased to give compound climate extremes, with melting glaciers in the South Island. How much more evidence (both scientific and lived experience) do we need to recognise that these are linked and plan accordingly?
India Today
02-05-2025
- Science
- India Today
Earth's oceans are surprisingly heating up around New Zealand
The world's oceans are heating at an accelerated rate within two specific regions, raising concerns about marine ecosystems and extreme weather study, led by climate scientist Dr. Kevin Trenberth, identifies these bands as located near 40 degrees latitude in both the northern and southern details of the findings have been published in the Journal of Climate. The southern band, situated between 40 and 45 degrees south, exhibits the most rapid heating, particularly around New Zealand, Tasmania, and the Atlantic waters east of the northern hemisphere, the band is centered around 40 degrees north, with the most significant warming occurring east of the United States in the North Atlantic and east of Japan in the North Pacific."This is very striking," stated Trenberth, affiliated with both the University of Auckland and the National Center of Atmospheric Research (NCAR). "It's unusual to discover such a distinctive pattern jumping out from climate data." The research highlights that ocean heating disrupts marine ecosystems. (Photo: Getty) The research highlights that ocean heating disrupts marine ecosystems, increases water vapour levels in the atmosphere (a potent greenhouse gas), and intensifies rainstorms and extreme weather 2005, these heat bands have developed in conjunction with poleward shifts in the jet stream and corresponding changes in ocean currents, according to Trenberth and his analysed an unprecedented volume of atmospheric and oceanic data, assessing 1-degree latitude strips of the ocean down to a depth of 2000 meters between 2000 and in heat content, measured in zettajoules, were compared against a baseline from 2000-2004. Significant heat increases were also observed in the tropics, between 10 degrees north and 20 degrees south, though these were less distinct due to variations caused by the El Nino-Southern Oscillation climate the subtropics near 20 degrees latitude in both hemispheres showed an absence of research team included Lijing Cheng and Yuying Pan from the Chinese Academy of Sciences, John Fasullo from NCAR, and Michael Mayer from the University of Vienna and the European Centre for Medium-Range Weather emphasised the role of greenhouse gases in climate change, noting that the resulting heat is primarily absorbed by the ocean, while also acknowledging the likely influence of natural Watch
Scoop
01-05-2025
- Science
- Scoop
Oceans Heating Faster In Two Bands Stretching Around Globe
Press Release – University of Auckland The world's oceans are heating faster in two bands stretching around the globe, and New Zealand is in one of them, according to new research led by climate scientist Dr Kevin Trenberth. In both hemispheres, the areas are near 40 degrees latitude. The first band at 40 to 45 degrees south is heating at the world's fastest pace, with the effect especially pronounced around New Zealand, Tasmania, and Atlantic waters east of Argentina. The second band is around 40 degrees north, with the biggest effects in waters east of the United States in the North Atlantic and east of Japan in the North Pacific. 'This is very striking,' says Trenberth, of the University of Auckland and the National Center of Atmospheric Research in Boulder, Colorado. 'It's unusual to discover such a distinctive pattern jumping out from climate data,' he says. Ocean heating upsets marine ecosystems, increases atmospheric levels of water vapour, which is a powerful greenhouse gas, and fuels rain-storms and extreme weather. The heat bands have developed since 2005 in tandem with poleward shifts in the jet stream, the powerful winds above the Earth's surface that blow from west to east, and corresponding shifts in ocean currents, according to Trenberth and his co-authors in the Journal of Climate. The scientists processed an 'unprecedented' volume of atmospheric and ocean data to assess 1 degree latitude strips of ocean to a depth of 2000m for the period from 2000 to 2023, Trenberth says. Changes in heat content, measured in zettajoules, were compared with a 2000-04 baseline. Besides the two key zones, sizeable increases in heat took place in the area from 10 degrees north to 20 degrees south, which includes much of the tropics. However, the effect was less distinct because of variations caused by the El Niño-Southern Oscillation climate pattern, Trenberth says. 'What is unusual is the absence of warming in the subtropics, near 20 degrees latitude, in both hemispheres,' he says. Co-authors of the paper were Lijing Cheng and Yuying Pan, of the Chinese Academy of Sciences, John Fasullo of NCAR, and Michael Mayer of the University of Vienna and the European Centre for Medium-Range Weather Forecasts. 'Despite what Donald Trump thinks, the climate is changing because of the build-up of greenhouse gases, and most of the extra heat ends up in the ocean,' says Trenberth. 'However, the results are by no means uniform, as this research shows. Natural variability is likely also at play.'
Scoop
01-05-2025
- Science
- Scoop
Oceans Heating Faster In Two Bands Stretching Around Globe
Press Release – University of Auckland The first band at 40 to 45 degrees south is heating at the worlds fastest pace, with the effect especially pronounced around New Zealand, Tasmania, and Atlantic waters east of Argentina. The world's oceans are heating faster in two bands stretching around the globe, and New Zealand is in one of them, according to new research led by climate scientist Dr Kevin Trenberth. In both hemispheres, the areas are near 40 degrees latitude. The first band at 40 to 45 degrees south is heating at the world's fastest pace, with the effect especially pronounced around New Zealand, Tasmania, and Atlantic waters east of Argentina. The second band is around 40 degrees north, with the biggest effects in waters east of the United States in the North Atlantic and east of Japan in the North Pacific. 'This is very striking,' says Trenberth, of the University of Auckland and the National Center of Atmospheric Research in Boulder, Colorado. 'It's unusual to discover such a distinctive pattern jumping out from climate data,' he says. Ocean heating upsets marine ecosystems, increases atmospheric levels of water vapour, which is a powerful greenhouse gas, and fuels rain-storms and extreme weather. The heat bands have developed since 2005 in tandem with poleward shifts in the jet stream, the powerful winds above the Earth's surface that blow from west to east, and corresponding shifts in ocean currents, according to Trenberth and his co-authors in the Journal of Climate. The scientists processed an 'unprecedented' volume of atmospheric and ocean data to assess 1 degree latitude strips of ocean to a depth of 2000m for the period from 2000 to 2023, Trenberth says. Changes in heat content, measured in zettajoules, were compared with a 2000-04 baseline. Besides the two key zones, sizeable increases in heat took place in the area from 10 degrees north to 20 degrees south, which includes much of the tropics. However, the effect was less distinct because of variations caused by the El Niño-Southern Oscillation climate pattern, Trenberth says. 'What is unusual is the absence of warming in the subtropics, near 20 degrees latitude, in both hemispheres,' he says. Co-authors of the paper were Lijing Cheng and Yuying Pan, of the Chinese Academy of Sciences, John Fasullo of NCAR, and Michael Mayer of the University of Vienna and the European Centre for Medium-Range Weather Forecasts. 'Despite what Donald Trump thinks, the climate is changing because of the build-up of greenhouse gases, and most of the extra heat ends up in the ocean,' says Trenberth. 'However, the results are by no means uniform, as this research shows. Natural variability is likely also at play.'
Scoop
01-05-2025
- Science
- Scoop
Oceans Heating Faster In Two Bands Stretching Around Globe
The world's oceans are heating faster in two bands stretching around the globe, and New Zealand is in one of them, according to new research led by climate scientist Dr Kevin Trenberth. In both hemispheres, the areas are near 40 degrees latitude. The first band at 40 to 45 degrees south is heating at the world's fastest pace, with the effect especially pronounced around New Zealand, Tasmania, and Atlantic waters east of Argentina. The second band is around 40 degrees north, with the biggest effects in waters east of the United States in the North Atlantic and east of Japan in the North Pacific. 'This is very striking,' says Trenberth, of the University of Auckland and the National Center of Atmospheric Research in Boulder, Colorado. 'It's unusual to discover such a distinctive pattern jumping out from climate data,' he says. Ocean heating upsets marine ecosystems, increases atmospheric levels of water vapour, which is a powerful greenhouse gas, and fuels rain-storms and extreme weather. The heat bands have developed since 2005 in tandem with poleward shifts in the jet stream, the powerful winds above the Earth's surface that blow from west to east, and corresponding shifts in ocean currents, according to Trenberth and his co-authors in the Journal of Climate. Advertisement - scroll to continue reading The scientists processed an 'unprecedented' volume of atmospheric and ocean data to assess 1 degree latitude strips of ocean to a depth of 2000m for the period from 2000 to 2023, Trenberth says. Changes in heat content, measured in zettajoules, were compared with a 2000-04 baseline. Besides the two key zones, sizeable increases in heat took place in the area from 10 degrees north to 20 degrees south, which includes much of the tropics. However, the effect was less distinct because of variations caused by the El Niño-Southern Oscillation climate pattern, Trenberth says. 'What is unusual is the absence of warming in the subtropics, near 20 degrees latitude, in both hemispheres,' he says. Co-authors of the paper were Lijing Cheng and Yuying Pan, of the Chinese Academy of Sciences, John Fasullo of NCAR, and Michael Mayer of the University of Vienna and the European Centre for Medium-Range Weather Forecasts. 'Despite what Donald Trump thinks, the climate is changing because of the build-up of greenhouse gases, and most of the extra heat ends up in the ocean,' says Trenberth. 'However, the results are by no means uniform, as this research shows. Natural variability is likely also at play."
