Thanks Richard, I trust NIWA temperature records and although we see slight warming during the past century in NZ it is only one tenth of one degree warmer each decade. I only consulted 20 years of temperature records which would imply only 0.2 degrees warmer and which is almost unnoticeable. In comparison the land in the northern hemisphere has warmed by 2.5 degrees during the same 100 year period. Am I right in assuming that atmospheric greenhouse gas levels are much the same all around the earth? If so, why has the northern hemisphere warmed almost three times faster than in the south? I am convinced of the anthropogenic cause, but what is the dominant anthropogenic factor?
The concentrations of man-made GHGs are slightly higher in the NH as that's where most are emitted. But the difference is small. SH concentrations lag those in the NH by only a couple of years.
I'm not sure which of these is the major factor for the NH SH differences, but all will no-doubt play a part
1. A much larger fraction of the SH is oceanic. The high specific heat of water means that when air comes in contact with the ocean surface, heat can be extracted to the water and then transported deep into the ocean (the oceans are also a net sinks for CO2, which contributed to the lag mentioned above).
2. Decreasing Arctic sea-ice cover lowers the surface albedo, allowing more energy to be absorbed in that region.
3. Increased concentrations of man-made aerosols - due to the larger population in the NH - can also trap energy.
4. Associated land-use changes may also alter the albedo, so changing the energy balance.
It's further complicated by changes in clouds which may be driven by several of the above factors...
Global warming is obvious to those who know how to evaluate scientific research and statistics while skeptics support their contrary position by quoting miscellaneous observations usually presented out of context or limited data and speculation. Here is my explanation why New Zealand has not experienced global warming and I look forward to any comments or a better explanation. https://www.brighteon.com/dashboard/videos/faeadf58-3925-4ac9-b790-2c038a21f45a
Thanks for passing that on. Temperature changes have been small in NZ, and are difficult to resolve in your plots. The small changes can also be masked by changes in instrument sites. The best record for NZ is the "Seven Stations Record" that was set up more than a decade ago. See here
Interesting theory about the melting ice, slowing the rate of increase in the SH, but I think the relatively small volume of ice involved compared with the huge volume of water makes that an unlikely explanation. However, as you suggest, changes in ocean circulation are undoubtedly an important factor (which explains why the warming is also smaller in regions affected by the weakening Gulf Stream).
Thanks Michael. Sorry, I don’t want to go to that site (which appears to be a repository for banned videos?). I’d be happy to look at your material if you can email it to me (rlm.uvb@gmail.com). Because if our maritime location, climate effects in NZ have been relatively small so far - compared with high northern latitudes for example. But there are well-documented effects including increased temperatures (both air and ocean), increases in growing degree-days, glacial retreat and reductions in snow cover, etc
Well said Richard! I’ve seen some of the gentleman’s rubbish on YouTube. Disheartening.
Totally agree with you. The naysayers are frightening.
Thanks Richard, I trust NIWA temperature records and although we see slight warming during the past century in NZ it is only one tenth of one degree warmer each decade. I only consulted 20 years of temperature records which would imply only 0.2 degrees warmer and which is almost unnoticeable. In comparison the land in the northern hemisphere has warmed by 2.5 degrees during the same 100 year period. Am I right in assuming that atmospheric greenhouse gas levels are much the same all around the earth? If so, why has the northern hemisphere warmed almost three times faster than in the south? I am convinced of the anthropogenic cause, but what is the dominant anthropogenic factor?
The concentrations of man-made GHGs are slightly higher in the NH as that's where most are emitted. But the difference is small. SH concentrations lag those in the NH by only a couple of years.
I'm not sure which of these is the major factor for the NH SH differences, but all will no-doubt play a part
1. A much larger fraction of the SH is oceanic. The high specific heat of water means that when air comes in contact with the ocean surface, heat can be extracted to the water and then transported deep into the ocean (the oceans are also a net sinks for CO2, which contributed to the lag mentioned above).
2. Decreasing Arctic sea-ice cover lowers the surface albedo, allowing more energy to be absorbed in that region.
3. Increased concentrations of man-made aerosols - due to the larger population in the NH - can also trap energy.
4. Associated land-use changes may also alter the albedo, so changing the energy balance.
It's further complicated by changes in clouds which may be driven by several of the above factors...
Global warming is obvious to those who know how to evaluate scientific research and statistics while skeptics support their contrary position by quoting miscellaneous observations usually presented out of context or limited data and speculation. Here is my explanation why New Zealand has not experienced global warming and I look forward to any comments or a better explanation. https://www.brighteon.com/dashboard/videos/faeadf58-3925-4ac9-b790-2c038a21f45a
Thanks for passing that on. Temperature changes have been small in NZ, and are difficult to resolve in your plots. The small changes can also be masked by changes in instrument sites. The best record for NZ is the "Seven Stations Record" that was set up more than a decade ago. See here
https://niwa.co.nz/climate-and-weather/nz-temperature-record/seven-station-series-temperature-data
Interesting theory about the melting ice, slowing the rate of increase in the SH, but I think the relatively small volume of ice involved compared with the huge volume of water makes that an unlikely explanation. However, as you suggest, changes in ocean circulation are undoubtedly an important factor (which explains why the warming is also smaller in regions affected by the weakening Gulf Stream).
Thanks Michael. Sorry, I don’t want to go to that site (which appears to be a repository for banned videos?). I’d be happy to look at your material if you can email it to me (rlm.uvb@gmail.com). Because if our maritime location, climate effects in NZ have been relatively small so far - compared with high northern latitudes for example. But there are well-documented effects including increased temperatures (both air and ocean), increases in growing degree-days, glacial retreat and reductions in snow cover, etc