Sentences with phrase «forcing has a warming effect»

Not exact matches

I'm not even an amateur climate scientist, but my logic tells me that if clouds have a stronger negative feedback in the Arctic, and I know (from news) the Arctic is warming faster than other areas, then it seems «forcing GHGs» (CO2, etc) may have a strong sensitivity than suggested, but this is suppressed by the cloud effect.

Since we know that the earth's surface is significantly warmed by geothermal heat, that geothermal heat is variable, that truly titanic forces are at work in the earth's core changing its structure and alignment, and that geothermal heat flux has a much greater influence on surface temperatures than variations in carbon dioxide can possibly have, it makes sense to include its effects in a compendium of global warming discussion parameters.

For global warming scenarios, additional forcing comes into play: surface warming and enhanced high - latitude precipitation, which will also reduce density of northern surface waters (an effect which alone has shut down deep water formation in some model experiments, e.g. Manabe and Stouffer 1993, 1994).

It's interesting to note that significant solar forcing would have exactly the opposite effect (it would cause a warming)-- yet another reason to doubt that solar forcing is a significant factor in recent decades.

This is a peer reviewed paper by respected scientists who are saying that aerosol forcing means that the majority of the warming caused by existing co2 emission has effectively been masked thus far, and that as aerosols remain in the atmosphere for far shorter a duration of time than co2, we will have already most likely crossed the 2 degree threshold that the G8 politicians have been discussing this week once the cooling effect of aerosols dissipate.

But more generally, something I've wondered is: while in the global annual average, aerosols could be said to partly cancel (net effect) the warming from anthropogenic greenhouse forcing, the circulatory, latitudinal, regional, seasonal, diurnal, and internal variability changes would be some combination of reduced changes from reduced AGW + some other changes related to aerosol forcing.

Given the total irrelevance of volcanic aerosols during the period in question, the only very modest effect of fossil fuel emissions and the many inconsistencies governing the data pertaining to solar irradiance, it seems clear that climate science has no meaningful explanation for the considerable warming trend we see in the earlier part of the 20th century — and if that's the case, then there is no reason to assume that the warming we see in the latter part of that century could not also be due to either some as yet unknown natural force, or perhaps simply random drift.

Before allowing the temperature to respond, we can consider the forcing at the tropopause (TRPP) and at TOA, both reductions in net upward fluxes (though at TOA, the net upward LW flux is simply the OLR); my point is that even without direct solar heating above the tropopause, the forcing at TOA can be less than the forcing at TRPP (as explained in detail for CO2 in my 348, but in general, it is possible to bring the net upward flux at TRPP toward zero but even with saturation at TOA, the nonzero skin temperature requires some nonzero net upward flux to remain — now it just depends on what the net fluxes were before we made the changes, and whether the proportionality of forcings at TRPP and TOA is similar if the effect has not approached saturation at TRPP); the forcing at TRPP is the forcing on the surface + troposphere, which they must warm up to balance, while the forcing difference between TOA and TRPP is the forcing on the stratosphere; if the forcing at TRPP is larger than at TOA, the stratosphere must cool, reducing outward fluxes from the stratosphere by the same total amount as the difference in forcings between TRPP and TOA.

(Note that radiative forcing is not necessarily proportional to reduction in atmospheric transparency, because relatively opaque layers in the lower warmer troposphere (water vapor, and for the fractional area they occupy, low level clouds) can reduce atmospheric transparency a lot on their own while only reducing the net upward LW flux above them by a small amount; colder, higher - level clouds will have a bigger effect on the net upward LW flux above them (per fraction of areal coverage), though they will have a smaller effect on the net upward LW flux below them.

Where you then have a talik, from this combination of geological and radiative forces, and then there is plenty of free gas underneath that can migrate out easily through pathways once there are such tears, and then you add on top of all that that it is a seismically active zone, one can easily see how global warming could greatly amplify the effects of an earthquake at that fault zone.

Warming must occur below the tropopause to increase the net LW flux out of the tropopause to balance the tropopause - level forcing; there is some feedback at that point as the stratosphere is «forced» by the fraction of that increase which it absorbs, and a fraction of that is transfered back to the tropopause level — for an optically thick stratosphere that could be significant, but I think it may be minor for the Earth as it is (while CO2 optical thickness of the stratosphere alone is large near the center of the band, most of the wavelengths in which the stratosphere is not transparent have a more moderate optical thickness on the order of 1 (mainly from stratospheric water vapor; stratospheric ozone makes a contribution over a narrow wavelength band, reaching somewhat larger optical thickness than stratospheric water vapor)(in the limit of an optically thin stratosphere at most wavelengths where the stratosphere is not transparent, changes in the net flux out of the stratosphere caused by stratospheric warming or cooling will tend to be evenly split between upward at TOA and downward at the tropopause; with greater optically thickness over a larger fraction of optically - significant wavelengths, the distribution of warming or cooling within the stratosphere will affect how such a change is distributed, and it would even be possible for stratospheric adjustment to have opposite effects on the downward flux at the tropopause and the upward flux aWarming must occur below the tropopause to increase the net LW flux out of the tropopause to balance the tropopause - level forcing; there is some feedback at that point as the stratosphere is «forced» by the fraction of that increase which it absorbs, and a fraction of that is transfered back to the tropopause level — for an optically thick stratosphere that could be significant, but I think it may be minor for the Earth as it is (while CO2 optical thickness of the stratosphere alone is large near the center of the band, most of the wavelengths in which the stratosphere is not transparent have a more moderate optical thickness on the order of 1 (mainly from stratospheric water vapor; stratospheric ozone makes a contribution over a narrow wavelength band, reaching somewhat larger optical thickness than stratospheric water vapor)(in the limit of an optically thin stratosphere at most wavelengths where the stratosphere is not transparent, changes in the net flux out of the stratosphere caused by stratospheric warming or cooling will tend to be evenly split between upward at TOA and downward at the tropopause; with greater optically thickness over a larger fraction of optically - significant wavelengths, the distribution of warming or cooling within the stratosphere will affect how such a change is distributed, and it would even be possible for stratospheric adjustment to have opposite effects on the downward flux at the tropopause and the upward flux awarming or cooling will tend to be evenly split between upward at TOA and downward at the tropopause; with greater optically thickness over a larger fraction of optically - significant wavelengths, the distribution of warming or cooling within the stratosphere will affect how such a change is distributed, and it would even be possible for stratospheric adjustment to have opposite effects on the downward flux at the tropopause and the upward flux awarming or cooling within the stratosphere will affect how such a change is distributed, and it would even be possible for stratospheric adjustment to have opposite effects on the downward flux at the tropopause and the upward flux at TOA).

Other forcings, including the growth and decay of massive Northern Hemisphere continental ice sheets, changes in atmospheric dust, and changes in the ocean circulation, are not likely to have the same kind of effect in a future warming scenario as they did at glacial times.

In addition there is still clear evidence in my view for aerosols having played a significant role in holding back that warming, which acts on top of the effects of internal variability which play an important role in fluctuations about the forced changes.

Subsidary question: as the ocean is quite a big part of the climate system, are it's temperature variations sufficiently constraint to corroborate the very interesting conclusion of Gavin's note: «It's interesting to note that significant solar forcing would have exactly the opposite effect (it would cause a warming)-- yet another reason to doubt that solar forcing is a significant factor in recent decades.»

``... point out that cooling trends are exactly as predicted by increasing greenhouse gas trends,... It is interesting to note that significant solar forcing would have exactly the opposite effect (it would cause warming)» (of the upper atmosphere)

As a non-scientist, it is reassuring that releases of Arctic methane should not force an apocalyptic runaway warming event, although the effects will still have very nasty consequences for our presently comfortable climate.

Multi-signal detection and attribution analyses, which quantify the contributions of different natural and anthropogenic forcings to observed changes, show that greenhouse gas forcing alone during the past half century would likely have resulted in greater than the observed warming if there had not been an offsetting cooling effect from aerosol and other forcings.

For instance, the warming that began in the early 20th century (1925 - 1944) is consistent with natural variability of the climate system (including a generalized lack of significant volcanic activity, which has a cooling effect), solar forcing, and initial forcing from greenhouse gases.

What do you think the radiative effect of CO2 would be as orbital forcing warms the oceans, permafrost etc?

If only GHG forcing is used, without aerosols, the surface temperature in the last decade or so is about 0.3 - 0.4 C higher than observations; adding in aerosols has a cooling effect of about 0.3 - 0.4 C (and so cancelling out a portion of the GHG warming), providing a fairly good match between the climate model simulations and the observations.

In 2007, Burnam also proposed a «global warming task force» that would have created a report studying the «global warming challenges and opportunities facing Texas» including «protecting public health from the effects of global warming.»

If we assume that the LIA was caused mostly by naturally forced variability, then we have several periods in the 20th century of cooling and warming associated with modest unforced variability: The AMO's effect on GMST (0.25 degC peak to trough) isn't big enough to invalidate the IPCC's attribution statement.

when skeptics are forced to answer that question, the only safe hiding place for them is to say «they do nt know what effect added GHGs will have» and then when confronted with the vast amount of evidence that counts «for» a warming hypothesis, it does nt seem rational reject the theory that added GHGs will (all things being equal) warm the planet.

His conclusion was that the CO2 forcing is unquestionably logarithmic, so that each additional molecule we emit has less forcing and warming effect than its predecessors; that the precise value of the coefficient in the CO2 forcing function, which the IPCC has already reduced by 15 %, can not be determined; and that, all things considered, 1 K per doubling was probably in the right ball - park.

So I think one would have to invoke a very strange climate delay effect in order to explain the recent warming with solar forcing.

But the net anthropogenic effect is warming, and that forcing is a long - term prospect and has been increasing in strength.

R Gates: «But the net anthropogenic effect is warming, and that forcing is a long - term prospect and has been increasing in strength.»

The simulated change of GM in the last 30 yr has a spatial pattern that differs from that during the Medieval Warm Period, suggesting that global warming that arises from the increases of greenhouse gases and the input solar forcing may have different effects on the characteristics of GM precipitation.

(PS — I don't remember my entire comment, but part of it had to do with the fact that in dividing up attribution for the forcings responsible for post-1950 warming, uncertainties regarding anthropogenic sulfate aerosols are not particularly important, because their net cooling effect wouldn't influence the percentage apportionment among the warming factors)

The causal case is a cumulative case of: 1) correlation + 2) well - evidenced mechanism (i.e. plausibility) + 3) primacy, where the proposed cause occurs before the effect + 4) robustness of the correlation under multiple tests / conditions + 5) experimental evidence that adding the cause subsequently results in the effect + 6) exclusion of other likely causes (see point 7 as well) + 7) specificity, where the effect having hallmarks of the cause (ex: the observed tropospheric warming and stratopsheric cooling, is a hallmark of greenhouse - gas - induced warming, not warming from solar forcing) 8) a physical gradient (or a dose - response), where more of the cause produces a larger effect, or more of the cause is more likely to produce the effect +....

The reasons enhanced GH warming does not produce a runaway warming are varied but the most basic answer is that CO2 forcing is logarithmic, not linear, so each additional ppm has less effect than the last.

The IPPC has long conceded that catastrophic AGW is impossible without some further unknown, unobserved and unmeasured magick mystery forcing to amplify the warming effect of CO2.

Clouds» impact on climate would obviously change as the world warms (a feedback) but, if solar - magnetic effects change clouds, as now seems likely, clouds could also drive climate change (a forcing).6, 7

But if you accept that the greenhouse effect is real, and that CO2 is a GHG, and that CO2 has increased (along with other GHGs), you have to accept the merit of my point: that solar, volcanoes, ocean currents and other natural variations do their thing, they vary, but GHGs exert a steady, constant upward forcing on temperature, which upward forcing is only offset by increased heat losses to space from a warmer planet.

In effect, what we see is that sea level rise due to human forced warming of the globe is starting to have a greater and greater impact on these shores.

(Parenthetically, if it were due to the sun, the same would apply, but elsewhere, Dr. Curry, I, and others have cited references indicating that solar forcing, even with some amplification beyond total solar irradiance, would have only minor moderating effects on significant anthropogenic warming even in the case of a severe solar lull.

That would seem to me to suggest that the effect of solar forcing compared to CO2 forcing has been underestimated, but it not would tell us much about the late 20C warming because there was no corresponding increase in solar activity.

Clearly the effects of urbanization have considerably exacerbated the warming experienced by the large majority of the Chinese population in comparison with the warming that they would have experienced as a result of external forcing alone.

A physicist is no more likely than a sociologist to know what human emissions will be 50 years from now — if a slight warming would be beneficial or harmful to humans or the natural world; if forcings and feedbacks will partly or completely offset the theoretical warming; if natural variability will exceed any discernible human effect; if secondary effects on weather will lead to more extreme or more mild weather events; if efforts to reduce emissions will be successful; who should reduce emissions, by what amounts, or when; and whether the costs of attempting to reduce emissions will exceed the benefits by an amount so large as to render the effort counterproductive.

In their Geophysical Research Letters publication the researchers also write that «aerosol invigoration effect occurs mainly in warmed - based convection with weak shear «-- as they could not find similar effects in frontal convection weather systems, which have higher wind shear and where air is forced up not by land surface warming, but by a pushing cold air wedge.

They note that their results are consistent with those of M2009, as the A2009 scenarios that yield 2 °C warming have 400 — 500 GtC emissions during 2000 — 2049; M2009 find 393 GtC emissions for 2 °C warming, but M2009 included a net warming effect of non-CO2 forcings, while A2009 neglected non-CO2 forcings.

And even if you can demonstrate an effect on cloud cover, clouds have both a cooling and a warming effect, what will the balance be and how much will that net forcing be?

In short, Lindzen's argument is that the radiative forcing from aerosols is highly uncertain with large error bars, and that they have both cooling (mainly by scattering sunlight and seeding clouds) and warming (mainly by black carbon darkening the Earth's surface and reducing its reflectivity) effects.

So why do L&S assume natural forcings have had a constant warming effect over the past 160 years?

You are saying this is not the dominant effect in the warming so far, and that even growing this forcing to 5 - 7 W / m2 is not going to have much effect, right?

Climate Science however was established with the premise that humans are having a catastrophic effect on the climate, primarily by forcing global warming through the emission of ACO2, and charged with the mission of confirming it.

The results of this analysis indicate that observed temperature after 1998 is consistent with the current understanding of the relationship among global surface temperature, internal variability, and radiative forcing, which includes anthropogenic factors that have well known warming and cooling effects.

The MWP is better explained by the Arctic Amplification effect whereas northern hemisphere warming is amplified due to faster thermal response to climate forcing due to greater land mass and less ocean mass; compared to the southern hemisphere which is largely water (which has a slower thermal inertial response to climate forcings).

: 1 there is a greenhouse effect 2 that CO2 is a GHG 3 that humans have increased atmospheric CO2 to levels not seen for 650k and more 4 that this MUST have a warming effect 5 that the warming (pattern, rate etc) is consistent with GHG forcing

1 there is a greenhouse effect 2 that CO2 is a GHG 3 that humans have increased atmospheric CO2 to levels not seen for 650k and more 4 that this MUST have a warming effect 5 that the warming (pattern, rate etc) is consistent with GHG forcing 5 that climate sensitivity is likely to be around 3C 6 that, whatever the flaws of MBH98, there are numerous hockey stick reconstructions developed by numerous (and independent) scientists using numerous proxies (not just treerings).