Sentences with phrase «observed over the past century»

Climate change models have typically underestimated the amount of sea level rise observed over the past century.

Generally, the remaining uncorrected effect from urban heat islands is now believed to be less than 0.1 C, and in some parts of the world it may be more than fully compensated for by other changes in measurement methods.4 Nevertheless, this remains an important source of uncertainty.The warming trend observed over the past century is too large to be easily dismissed as a consequence of measurement errors.

As we will see here, natural variability can not account for the large and rapid warming we've observed over the past century, and particularly the past 40 years.

A favorite argument among climate scientist «skeptics» like Christy, Spencer, and Lindzen is that «internal variability» can account for much or all of the global warming we've observed over the past century.

Even the climate we have observed over the past century or so is only one realization of what the real system might produce.

«Despite a wide range of climate sensitivity (i.e. the amount of surface temperature increase due to a change in radiative forcing, such as an increase of CO2) exhibited by the models, they all yield a global average temperature change very similar to that observed over the past century.

The modelers got a good match to maps of the climate changes observed over the past century, but only if they included the effects of the gases, and not if they tried to attribute it all to the Sun.

Not exact matches

In particular, the modelers could now reproduce in detail the pattern of warming, changes in rainfall, etc. actually observed in different regions of the world over the past century.

Indeed, tree - ring chronologies provide much longer histories than observational records and corroborate that variability and synchrony have risen over the past hundred years, and to levels that are as high as any observed over the past three centuries, according to the researchers.

«We have shown that internal global climate - system variability accounts for at least 80 % of the observed global climate variation over the past half - century.

Even the IPCC does not concur, stating that the «Current datasets indicate no significant observed trends in global tropical cyclone frequency over the past century and it remains uncertain whether any reported long - term increases in tropical cyclone frequency are robust.»

The actual prevailing view of the paleoclimate research community that emerged during the early 1990s, when long - term proxy data became more widely available and it was possible to synthesize them into estimates of large - scale temperature changes in past centuries, was that the average temperature over the Northern Hemisphere varied by significantly less than 1 degree C in previous centuries (i.e., the variations in past centuries were small compared to the observed 20th century warming).

While the observed Antarctic temperatures rose by about 0.4 degrees Fahrenheit (0.2 degrees Celsius) over the past century, the climate models simulated increases in Antarctic temperatures during the same period of 1.4 degrees F (0.75 degrees C).

Moreover, greenhouse gas concentration increases of the magnitude observed over the past two centuries have in the past occured only taken place on timescales of millions of years.

-- I calculated potential intensity trends over the period 1980 - 2012 & The disparity between the reanalysis potential intensity trends over the past 30 years and the projected trends over this century suggests either that most of the observed increase in potential intensity (and actual intensity of high category storms) is due to natural variability,....»

For the station nearest my home, the range (max less min) in annual average temperature for the past century is just 3.3 C. Can't say whether 1C warming matters in any tangible way, at this particular spot, but it's certainly large compared to the variation observed over the last century.

States that while no significant trends have been identified in the Atlantic since the late 19th century, significant observed trends in TC numbers and intensities have occurred in this basin over the past few decades, and trends in other basins are increasingly being identified

Some of these climate drivers result in warming and others lead to cooling, but when all the natural and human - induced climate drivers are stacked up and compared to one another, the accumulation of human - released heat - trapping gases in the atmosphere is so large that it has very likely swamped other climate drivers over the past half century, leading to observed global warming.

«Current datasets indicate no significant observed trends in global tropical cyclone frequency over the past century» 2.

This is indeed the average rate as observed over the past 27 centuries.»

Volcanic activity proceeds over the decades at a level of only about 1 percent of industrial CO2 emissions, and even major eruptions observed during the past century have changed atmospheric CO2 trends only minimally and transiently.

As Figure 3 shows, the body of scientific literature is still very consistent in finding that grenhouse gases have most likely caused more warming than has been observed over the past half century, and thus that the IPCC has been too conservative in this respect.

Extending the sea level record back over the entire century suggests that the high variability in the rates of sea level change observed over the past 20 years were not particularly unusual.

«To conclude, modeled atmospheric circulation and SST trends over the past century are significantly different from the observed ones.

The observed warming over the past century, even if it were all due to increases in carbon dioxide, would not imply any greater warming.

Jones et al., 2016 http://www.nature.com/nclimate/journal/v6/n10/full/nclimate3103.html «Most observed trends [over the 36 - year satellite data] are not unusual when compared with Antarctic palaeoclimate records of the past two centuries.

As he pointed out, a dominant unforced contribution to surface warming relative to forced trends would be expected to be accompanied by a trend of declining OHC, which is inconsistent with the observed trends averaged over the past half century as evidenced by mixed layer temperature measurements and sea level rise.

Even while identifying some of the observed change in climatic behaviour, such as a 0.4 C increase in surface temperature over the past century, or about 1 mm per year sea level rise in Northern Indian Ocean, or wider variation in rainfall patterns, the document notes that no firm link between the do...

But very few people know that the same situation has persisted for 25, going on 35 years, or that over the past 50 - 60 years (since the middle of the 20th century), the same models expected about 33 percent more warming to have taken place than was observed.

Over the past several centuries, human greenhouse gas emissions have caused by far the largest radiative forcing (energy imbalance), and thus must be the driver of any observed long - term global warming.

Thus, the pattern of declining δ13C over the past decade at Tatoosh Island has not been observed at any other time over past decades and centuries.

Despite dataset and modelling uncertainty, these results, together with the understanding of the causes of observed warming over the past century, provide substantial evidence of a human contribution to the observed decline in Northern Hemisphere spring snow cover extent.

We show that although increases in greenhouse - gas concentrations have driven the observed warming over the past century, approximately 60 % of the greenhouse - gas - induced warming has been offset by the combined response to other anthropogenic forcings, which is substantially greater than the fraction of global greenhouse - gas - induced warming that has been offset by these forcings.

Mickley et al. (2001) find that observed long - term trends in ozone over the past century might be explainable by an increase in lightning.

The fundamental conclusion in Lean and Rind's paper is that the observed global warming over the past century, and especially over the past 25 - 50 years, is predominantly human - caused:

Still, the extent of sea ice recorded in November was well shy of the median extent observed over the past quarter century, as the image from Nov. 14 (above, right) shows.

Since urbanization has grown dramatically over the past few centuries, it seems reasonable to ask how much of the observed rise in global temperatures is due to urbanization.

Gavin points out that if Salby's model truly explained most or all of the 100 ppm observed rise in CO2 based on the 0.8 C rise in global temperature over the past century, that would imply a massive sensitivity of the CO2 flux to global temperatures.

Over the past century, the Bureau has expanded, developed and advanced its network of observing sites.

In the composite effect (f), the greenhouse gas forcing dominates due to its predominance in observed climate change over the past century.

Over the past two centuries, forest conversion and forest management have contributed a substantial fraction of the excess CO2 observed in the atmosphere.

The models heavily relied upon by the Intergovernmental Panel on Climate Change (IPCC) had not projected this multidecadal stasis in «global warming»; nor (until trained ex post facto) the fall in TS from 1940 - 1975; nor 50 years» cooling in Antarctica (Doran et al., 2002) and the Arctic (Soon, 2005); nor the absence of ocean warming since 2003 (Lyman et al., 2006; Gouretski & Koltermann, 2007); nor the onset, duration, or intensity of the Madden - Julian intraseasonal oscillation, the Quasi-Biennial Oscillation in the tropical stratosphere, El Nino / La Nina oscillations, the Atlantic Multidecadal Oscillation, or the Pacific Decadal Oscillation that has recently transited from its warming to its cooling phase (oceanic oscillations which, on their own, may account for all of the observed warmings and coolings over the past half - century: Tsoniset al., 2007); nor the magnitude nor duration of multi-century events such as the Mediaeval Warm Period or the Little Ice Age; nor the cessation since 2000 of the previously - observed growth in atmospheric methane concentration (IPCC, 2007); nor the active 2004 hurricane season; nor the inactive subsequent seasons; nor the UK flooding of 2007 (the Met Office had forecast a summer of prolonged droughts only six weeks previously); nor the solar Grand Maximum of the past 70 years, during which the Sun was more active, for longer, than at almost any similar period in the past 11,400 years (Hathaway, 2004; Solankiet al., 2005); nor the consequent surface «global warming» on Mars, Jupiter, Neptune's largest moon, and even distant Pluto; nor the eerily - continuing 2006 solar minimum; nor the consequent, precipitate decline of ~ 0.8 °C in TS from January 2007 to May 2008 that has canceled out almost all of the observed warming of the 20th century.

None of these could have been caused by an increase in atmospheric CO2, Model projections of warming during recent decades have greatly exceeded what has been observed, The modelling community has openly acknowledged that the ability of existing models to simulate past climates is due to numerous arbitrary tuning adjustments, Observations show no statistically valid trends in flooding or drought, and no meaningful acceleration whatsoever of pre-existing long term sea level rise (about 6 inches per century) worldwide, Current carbon dioxide levels, around 400 parts per million are still very small compared to the averages over geological history, when thousands of parts per million prevailed, and when life flourished on land and in the oceans.

The pattern of modeled surface temperature changes induced by solar variability is well correlated with observed global warming over the first half of the 20th century, but not with the more rapid warming seen over the past three decades.

In the case of global mean surface temperature, the IPCC AR5 presents a strong body of scientific evidence that most of the global warming observed over the past half century is very likely due to human - caused greenhouse gas emissions.

When the phase of natural variability is taken into account, the model 15 - year warming trends in CMIP5 projections well estimate the observed trends for all 15 - year periods over the past half - century.