Response to comments:

The 3 comments above do not appear to be based on the peer review literature nor on recent reports by NOAA, NASA, NSIDC, Hadley-Met, Tyndall, Potsdam Climate Impacts, CSIRO, BOM, the world’s academies of Science, IPCC -, the list goes on.

An up-to-date report by NOAA "State of the Climate in 2010"
http://www.ncdc.noaa.gov/bams-state-of-the-climate/2010.php
presents comprehensive global and regional accounts of global and regional climate states and trends, providing answers to many of the questions.

Specifically in response to the comments above:

James:

The reference you refer to
http://www.the-cryosphere-discuss.net/5/1311/2011/tcd-5-1311-2011.html states:
“Arctic sea ice area decrease has been visible for two decades, and continues at a steady rate. Apart from melting, the southward drift through Fram Strait is the main loss.”

I assume you realize the difference between the ehaviour of sea ice and continental ice sheets. Expansion and contraction of sea ice, with thicknesses on the scale of meters to tens of meters, constitutes a “fast feedback” responding to annual and multiannual changes in atmospheric and sea water temperatures and winds. By contrast continental ice sheets, up to 2-3 km thick, grow or thin in response to longer term climate trends. Se reports of recent satellite gravity measurements (Rignot and Velicogna, 2011; Hansen and Sato, 2011; Hansen et al, 2011) “Melting ice sheets becoming largest contributor to sea level rise” http://www.agu.org/news/press/pr_archives/2011/2011-09.shtml

The second paper you refer to: Recent historically low global tropical cyclone activity by R. Mauel http://www.coaps.fsu.edu/~maue/tropical/2011GL047711-pip.pdf does not appears to be a peer review paper.

The frequency of cyclones and hurricanes varies regionally, whereas the intensity of these events has increased, consistent with the rise in sea water temperatures, i.e. Webster, P.J., Holland, G.J., Curry, J.A., Chang, H.R., 2005. Changes in Tropical Cyclone Number, Duration, and Intensity in a Warming Environment, Science, 309, 1844-1846.

Reports by the Munich Re-insurance which documents natural events around the world indicates the frequency of global natural catastrophes has doubled during 1998 – 2008 https://www.munichre.com/touch/login/en/service/login.aspx?ReturnUrl=/touch/publications/en/list/default.aspx?id=1060

Marc:

You state: “Andrew is hanging his hat on a forcing whose level of scientific understanding is described by the IPCC as "Low to medium". The direct affect of aerosols is estimated by the IPCC to be -0.5 W.m-2 +/- 0.4 W.m-2 (that's +/- 80%!). “

According to the IPCC AR4 2007 The direct effects of aerosols are:

-0.5 watt/m2 for direct albedo effects
-0.7 watt/m2 for cloud albedo effects

The total of -1.2 Watt/m2 is consistent with estimates in Hansen et al.’s 2011 new paper “Earth energy balance and implications” http://arxiv.org/abs/1105.1140
For Charney’s climate sensitivity of 3C per doubling of CO2 this means a sulphur albedo-masked T rise of +0.9C.

For a comprehensive discussion of the history of the atmosphere with reference to climate change refer to my 2008 paper “Milestones in the evolution of the atmososphere” http://www.google.com.au/search?q=ajes+glikson+milestone+atmosphere&rls=com.microsoft:en-us:IE-SearchBox&ie=UTF-8&oe=UTF-8&sourceid=ie7&rlz=1I7ADFA_en

John:

Regarding credible evidence for the infrared absorption/ emission properties of greenhouse gases, a good summary is at “The CO2 greenhouse effect”: http://www.aip.org/history/climate/co2.htm plus numerous papers in the peer review literature, an excellent one being “Trace gases and climate change” http://rsta.royalsocietypublishing.org/content/365/1856/1925.abstract.

The summary states: Palaeoclimate data show that the Earth's climate is remarkably sensitive to global forcings. Positive feedbacks predominate. This allows the entire planet to be whipsawed between climate states. One feedback, the ‘albedo flip’ property of ice/water, provides a powerful trigger mechanism. A climate forcing that ‘flips’ the albedo of a sufficient portion of an ice sheet can spark a cataclysm. Inertia of ice sheet and ocean provides only moderate delay to ice sheet disintegration and a burst of added global warming. Recent greenhouse gas (GHG) emissions place the Earth perilously close to dramatic climate change that could run out of our control, with great dangers for humans and other creatures. Carbon dioxide (CO2) is the largest human-made climate forcing, but other trace constituents are also important. Only intense simultaneous efforts to slow CO2 emissions and reduce non-CO2 forcings can keep climate within or near the range of the past million years. The most important of the non-CO2 forcings is methane (CH4), as it causes the second largest human-made GHG climate forcing and is the principal cause of increased tropospheric ozone (O3), which is the third largest GHG forcing. Nitrous oxide (N2O) should also be a focus of climate mitigation efforts. Black carbon (‘black soot’) has a high global warming potential (approx. 2000, 500 and 200 for 20, 100 and 500 years, respectively) and deserves greater attention. Some forcings are especially effective at high latitudes, so concerted efforts to reduce their emissions could preserve Arctic ice, while also having major benefits for human health, agricultural productivity and the global environment.

Wish you were right when you state “The absence of warming (or negiligible warming, depending who one speaks to) over the last 10 years is easily explained“. Unfortunately the last decade was the warmest on record, as indicate by temperature data by NOAA, NASA, NSIDC, Hadley-Met, Tyndall, Potsdam Climate Impacts,CSIRO, BOM, the world’s academies of Science.

Regarding ENSO, I read your earlier paper " Influence of the Southern Oscillation on tropospheric temperature in JGR where you claim “natural forcing mechanisms to account for most of the temperature variation.”, as well as the response by Foster et al. 2010 indicating: “The suggestion in their conclusions that ENSO may be a major contributor to recent trends in global temperature is not supported by their analysis or any physical theory presented in that paper, especially as the analysis method itself eliminates the influence of trends on the purported correlations. “

In summary, climate change constitutes a decade-scale trend. By contrast, those who attempt to refute the evidence:

1. Refer to annual to multiannual variations (i.e. sea ice, precipitation, ENSO cycle) rather than decade-scale trends.

2. Overlook the basic physical laws of black body radiation and infrared absorption/radiation by greenhouse gas molecules (Planck law, Stefan-Bolzman law).

3. Mostly ignore the peer review literature

Regarding the comment above "You rely heavily on the cooling effect of aerosols to help explain the poor performance of climate models to account for the lack no warming."

Lack of warming?

The figure in my article shows warming of the polar regions to above 4 degrees C , which is what drives melting of the continental ice sheets reported from satellite gravity measurements (Rignot and Velicogna 2011).

Regarding the aerosol effect, the IPCC AR4 2007 indicates the following in figure SPM2:
CO2 +1.66 Watt/m2
CH4 +0.48 watt/m2
N2O +0.16 Watt/m2
Halocarbons +0.34 Watt/m2
Net anthropogenic forcing +1.6 Watt/m2: Translate the net to temperature according to Charney's CS value of 3C per doubling of CO2 yields warming by +1.2 degrees C, consistent with Hansen et al.'s paper "Earth's energy imbalance and implications".

The residence time of sulphur aerosols in the atmosphere is only a few years, which means, should the cooling effect of sulphur aerosols decline or cease, temperatures would rise accordingly.

The summary of Hansen't et al.'s paper states:

“Direct aerosol Improving observations of ocean temperature confirm that Earth is absorbing more energy from the sun than it is radiating to space as heat, even during the recent solar minimum. The inferred planetary energy imbalance, 0.59 ± 0.15 W/m2 during the 6-year period 2005-2010, provides fundamental verification of the dominant role of the human-made greenhouse effect in driving global climate change. Observed surface temperature change and ocean heat gain constrain the net climate forcing and ocean mixing rates. We conclude that most climate models mix heat too efficiently into the deep ocean and as a result underestimate the negative forcing by human-made aerosols. Aerosol climate forcing today is inferred to be 1.6 ±0.3 W/m2, implying substantial aerosol indirect climate forcing via cloud changes. Continued failure to quantify the specific origins of this large forcing is untenable, as knowledge of changing aerosol effects is needed to understand future climate change. A recent decrease in ocean heat uptake was caused by a delayed rebound effect from Mount Pinatubo aerosols and a deep prolonged solar minimum. Observed sea level rise during the Argo float era can readily be accounted for by thermal expansion of the ocean and ice melt, but the ascendency of ice melt leads us to anticipate a near-term acceleration in the rate of sea level rise.”

No one expects the "all the necessary detail" to appear in an internet article or on a thread - the best that can be done for those who are interested in what the peer-reviewed science says is to point out the latest comprehensive reports and reviews, including the lists of references they contain.

In this case, the latest report, based on the most up to date peer reviewed literature, is Professor Will Steffen's report "The Critical Decade" and the references therein.
http://climatecommission.gov.au/topics/the-critical-decade/

I will be pleased to clarify technical points in this report if required.

James,

You write: "Andrew, could you please explain what is meant by "near term" and "acceleration" in this context? Do you mean that over the next 10 years sea level rise will be > 3.1mm/yr long term trend? If the proponents of GCR aerosols are right we should expect deceleration of sea level rise, and if similar cooling occurs as in the Maunder and Dalton minimums perhaps even european glacial advancement.... This will be something we get to observe which is quite exciting.

Response:

1. Sea level rise has been acceelrating from about 1.6 mm/year in 1970 to about 3.5 mm/year in 2006 (Rahmstorf 2007, Fig. 3 in Science, 315). Decceleration of ice melt and sea level rise took place between theend of WWII and 1970 in connection with heavy industrial emission of aerosols and a lull in the 11 year sun spot cycle (Google Rahmstorf / 2007 / sea level rise).

2. The Maunder minimum is related to several decades of near-disappearance of sun spots. Temperature variations related to the 11-years sunspot cycle are in the range of +/-0.1 degrees C, near an order of magnitude less than that of measured since the 18th century.

3. Had it not been for the transient (several years-long atmospheric residence time) effect of mainly sulphur aerosols mean global temepratures would be near 2.3 degrees C, more than 20 times the solar-induced variations.

4. Science, as distinct from "futurology", can not predict precise levels of temperature, ice melt and sea level rise - but it projects TRENDS consistent with the basic laws of physics and with measurements of past and present variations in these parameters. This is because the "experiment" humaity is currently conducting with the atmosphere has no percise precedence. However, we know that every time CO2 and methane levels rose during the history of Earth this was associated with temperature rises. In some instances the GHG rise drove temperatures, in other cases CO2 rise followed warming triggered by other drivers, as during the glacial terminations, when orbital forcings and amplified ice melt resulted in warming of the oceans and release of CO2. No solar triggers occurred since about 14,000 years ago.

The peer review literature and internet blog pieces reside in parallel universes. People can chose the first, published by practicing scientists with many years experience, or the latter, expressing opinions. The best way for those concerned with the climate is to look directly at authentic data sets reported by the world's premier climate science organizations (NOAA, NASA, NSIDC, Hadley-Met, Potsdam, CSIRO, BOM and so on) and draw their own conclusions from the trends.

Here's Judy Curry's take on the sulphur claims following publication of a PNAS paper that recognizes there has been NO warming since 1998.

The paper is "Reconciling anthropogenic climate change with observed temperature 1998-2008."

The first line of the Abstract reads..."Given the widely noted increase in the warming effects of rising greenhouse gas concentrations, it has been unclear why global surface temperatures did not rise between 1998 and 2008."

Judy Curry comments...
"This paper points out that global coal consumption (primarily from China) has increased significantly, although the dataset referred to shows an increase only since 2004-2007 (the period 1985-2003 was pretty stable). The authors argue that the sulfates associated with this coal consumption have been sufficient to counter the greenhouse gas warming during the period 1998-2008, which is similar to the mechanism that has been invoked to explain the cooling during the period 1940-1970.

I don’t find this explanation to be convincing because the increase in sulfates occurs only since 2004 (the solar signal is too small to make much difference). Further, translating regional sulfate emission into global forcing isnt really appropriate, since atmospheric sulfate has too short of an atmospheric lifetime (owing to cloud and rain processes) to influence the global radiation balance.

The alternative explanation is natural internal variability associated with the ocean oscillations. Since 1999, the Pacific Decadal Oscillation has been shifting from the warm phase (warm phase since 1976) to the cool phase, and has been mostly in the cool phase since 2007. A cool PDO is associated with more frequent La Nina events, which are associated with globally cooler temperatures. The climate model studies cited by the authors do not do a convincing job of ruling out natural internal variability as an explanation, either for the cool period since 1998, and the earlier cool period during 1940-1970.

In summary, the authors have put forward one possible explanation for the lack of warming, but an explanation associated with natural internal variability associated with the ocean oscillations is at least as plausible as the explanation put forward by the authors."

See Judy's full post at:
http://judithcurry.com/2011/07/04/an-explanation-for-lack-of-warming-since-1998/#more-3966