Global Average Change Research Articles

Rapidly Changing East Asian Marine Heatwaves Under a Warming Climate

AbstractThe East Asian marginal seas (EAMS) are one of the fastest‐warming ocean regions globally. This study presents the long‐term trends (1982–2020) of extreme ocean warming events called “marine heatwaves” over the EAMS and examines the relationships between marine heatwave trends and mean SST warming trends. We focus on five subregions with different influences from atmospheric perturbation and ocean currents: the northern East Sea (N‐ES), southern East Sea, Yellow Sea, Korea Strait (KS), and East China Sea (ECS). During the past four decades, marine heatwave duration and intensity in the EAMS have increased to approximately +4 days and +0.3°C per decade on average, respectively. In summer, the positive trend of marine heatwaves is the highest in the ECS, primarily due to the rapidly increasing mean sea surface temperature (SST). In winter, the N‐ES reveals remarkably rapid increases in marine heatwave properties in the last two decades, with increasing rates of approximately 6.2 (4.9) times longer total duration (stronger intensity) than the global average changes. Beyond the impact of the rapid increase in mean SST, the N‐ES marine heatwaves can be further extended due to the northward shift of the East Korea Warm Current. In general, mean SST changes are critical to the increasing trend in marine heatwave duration and intensity. This study further emphasizes that the changes in ocean circulation may expedite more rapid changes in extreme ocean events, which can produce more vulnerability in some places, such as the N‐ES, to marine heatwaves under continued global warming.

Impacts of tiled land cover characterization in the Model for Prediction Across Scales-Atmosphere (MPAS-A).

Parameterization of subgrid-scale variability of land cover characterization (LCC) is an active area of research, and can improve model performance compared to the dominant (i.e., most abundant tile) approach. The "Noah" land surface model implementation in the global Model for Predictions Across Scales-Atmosphere (MPAS-A), however, only uses the dominant LCC approach that leads to oversimplification in regions of highly heterogeneous LCC (e.g., urban/suburban settings). Thus, in this work we implement a subgrid tiled approach as an option in MPAS-A, version 6.0, and assess the impacts of tiled LCC on meteorological predictions for two gradually refining meshes (92-25 and 46-12 km) focused on the conterminous U.S for January and July 2016. Compared to the dominant approach, results show that using the tiled LCC leads to pronounced global changes in 2-m temperature (July global average change ~ -0.4 K), 2-m moisture, and 10-m wind speed for the 92-25 km mesh. The tiled LCC reduces mean biases in 2-m temperature (July U.S. average bias reduction ~ factor of 4) and specific humidity in the central and western U.S. for the 92-25 km mesh, improves the agreement of vertical profiles (e.g., temperature, humidity, and wind speed) with observed radiosondes; however, there is increased bias and error for incoming solar radiation at the surface. The inclusion of subgrid LCC has implications for reducing systematic temperature biases found in numerical weather prediction models, particularly those that employ a dominant LCC approach.

45P - The challenge of evaluating new targeted therapies: Opportunities in stratifying the therapeutic response per tumour location

BackgroundCompared with conventional cancer chemotherapy, tyrosine kinase inhibitors show novel patterns of radiology response, therefore using chemotherapy-based response criteria can be suboptimal. Coupling the tumor’s volume as an imaging biomarker with a stratified analysis of the therapeutic response per sites of disease may offer more insightful information in drug efficacy. We propose to compare the therapeutic response between Varlitinib plus Capecitabine (VC) and Lapatinib plus Capecitabine (LC) in analyzing the changes of tumor’s volume per tumor’s locations in patients with HER2-positive metastatic breast cancer after trastuzumab therapy. MethodsWe retrospectively analyzed data from the ASLAN001-003 study (NCT02338245). At baseline, 42 patients displayed at least one target lesion, representing a set of 88 target lesions: Lung (31%), Breast (26%), liver (23%), nodes (17%), miscellaneous (3%). Responses were evaluated at week 12 on 35 patients (14 VC; 21 LC). Between two arms, we compared responses using non-parametric tests and compared the proportion of tumor at each location using the Chi-square test. We used the R software for statistics, p < 0.05 was considered a significant difference. ResultsThe distribution of tumor size at baseline was different at the different tumor locations (p < 0.001). Between the two arms the proportion of tumor at each location were not equivalent with p = 0.126 and 0.06 for breast and lung tumors respectively. The global average change from baseline was VC=-64.1% and LC=-26.59% (p = 0.13) The average change of breast tumors was significantly different in the VC (-84.2%) and the LC (-24.9%) (p < 0.001) arm. Between breast and liver tumors, the average response was significantly different (p = 0.007) in the VC arm, while not in the LC arm (p = 0.94). Also, between nodal and liver tumors with p = 0.06 in the VC and p = 0.99 in LC arm. ConclusionsThe therapeutic response differed across tumor locations, the differential response was drug-dependent. For a fair comparison, the proportion of tumor at each tumor location must be balanced between arms. The stratification of the therapeutic response can be used for assessing new therapies, helping designing cocktails or refining drug’s indications. Clinical trial identificationASLAN001-003 - NCT02338245. Legal entity responsible for the studyMedian Technologies/Aslan Pharmaceuticals. FundingHas not received any funding. DisclosureH. Beaumont: Full / Part-time employment: Median Technologies. N. Faye: Full / Part-time employment: Median Technologies. C. Klifa: Full / Part-time employment: Median Technologies. C-Y. Hsieh: Full / Part-time employment: Aslan Pharmaceuticals. All other authors have declared no conflicts of interest.

Impacts of climate warming on maximum aviation payloads

The increasing importance of aviation activities in modern life coincides with a steady warming climate. However, the effect of climate warming on maximum aircraft carrying capacity or payload has been unclear. Here we clarify this issue using primary atmospheric parameters from 27 fully coupled climate models from the Coupled Model Inter-comparison Project 5 (CMIP5) archive, utilizing the direct proportionality of near-surface air density (NSAD) to maximum take-off total weight (MTOW). Historical (twentieth century) runs of these climate models showed high credibility in reproducing the reanalysis period (1950–2015) of NSAD. In particular, the model simulated trends in NSAD are highly aligned with the reanalysis values. This reduction in NSAD is a first order global signal, just as is the warming itself, that continues into the future. To examine the statistical significance of the density reduction, a t-test was performed for two 20-year periods 75 years apart (2080–2100 vs. 2005–2025), using the Representative Concentration Pathways (RCP) 8.5 emission scenario of the Intergovernmental Panel on Climate Change (IPCC). Most continental areas easily passed the test at a P-value of 0.05. These future changes of NSAD will likely have significant economic impacts on the aviation industry. For these two 20-year periods that we examined, the most extreme changes are in the Northern hemisphere in high latitudes, i.e., a 5% decrease in MTOW, or ~ 8.5–19% (aircraft-dependent) reduction in payload. The global average change is about 1%. For the busy North Atlantic Corridor (NAC), the reduction in MTOW is generally greater than 1% and that of payload several times larger.

Deglaciation-Induced Spatially Variable Sea Level Change: A Simple-Model Case Study for the Greenland and Antarctic Ice Sheets

Some studies on deglaciation-induced sea level change provide only a global average change, thus neglecting the fact that sea level change is spatially variable. This is due mainly to the gravitational and visco-elastic feedback effects of the changing surface mass loads. In order to address this apparent misconception and raise further awareness, we provide a conceptual example based on a simulated total melt of the Greenland and Antarctic ice sheets. This would give a global average sea level change of about 64 m. However, due to the changed distribution of gravitating masses, the sea-level change depends on location, with a range of about −27 m to +79 m (i.e., sea-level will even fall in some places). This spatial dependency has several implications, such as &gt;10% biases in global average sea-level change estimates based only on tide-gauge records, flooding of almost 10% of current land areas, an increase of the length of day by almost a half a second and a northward move of the centre of mass (geocentre) by about 20 m.

Decadal Trends in Sea Level Patterns: 1993–2004

AbstractEstimates of regional patterns of global sea level change are obtained from a 1° horizontal resolution general circulation model constrained by least squares to about 100 million ocean observations and many more meteorological estimates during the period 1993–2004. The data include not only altimetric variability, but most of the modern hydrography, Argo float profiles, sea surface temperature, and other observations. Spatial-mean trends in altimetric data are explicitly suppressed to isolate global average long-term changes required by the in situ data alone. On large scales, some regions display strong signals although few individual points have statistically significant trends. In the regional patterns, thermal, salinity, and mass redistribution contributions are all important, showing that regional sea level change is tied directly to the general circulation. Contributions below about 900 m are significant, but not dominant, and are expected to grow with time as the abyssal ocean shifts. Estimates made here produce a global mean of about 1.6 mm yr−1, or about 60% of the pure altimetric estimate, of which about 70% is from the addition of freshwater. Interannual global variations may be dominated by the freshwater changes rather than by heating changes. The widely quoted altimetric global average values may well be correct, but the accuracies being inferred in the literature are not testable by existing in situ observations. Useful estimation of the global averages is extremely difficult given the realities of space–time sampling and model approximations. Systematic errors are likely to dominate most estimates of global average change: published values and error bars should be used very cautiously.

The Sensitivity of the Radiation Budget in a Climate Simulation to Neglecting the Effect of Small Ice Particles

Abstract The sensitivity of the atmospheric radiation budget to ignoring small ice particles (D ≤ 100 μm) in parameterization of the mean effective size of ice particles was investigated by using the Canadian Centre for Climate Modelling and Analysis (CCCma) third-generation general atmospheric circulation model (AGCM3). The results indicate that small ice particles play two crucial roles in the radiative transfer that influence the simulated climate. First, they inhibit the IR radiation from escaping to space and, second, they enhance the scattering of solar radiation. On average, these two effects tend to partially cancel each other out. However, based on AGCM simulations, the small ice crystals make clouds more opaque to IR radiation. Generally, 5-yr seasonally averaged GCM results suggest that the strongest anomalies in outgoing longwave radiation (OLR) are found in the Tropics, reaching 15 to 25 W m−2 in areas where cold high cirrus anvil clouds are prevalent. The global average change in net cloud radiative forcing was 2.4 W m−2 in June–August (JJA) and 1.7 W m−2 in December–February (DJF). The change in globally averaged 5-yr mean cloud forcing was close to 1.9 W m−2. When the small particles were included, the globally averaged 5-yr mean precipitation decreased by about 8%, but cloudiness increased only slightly (by 2%). The 5-yr averaged global mean surface (screen) temperature also increased slightly (about 0.2°C) when the small ice particles were included.

Ground based VLF observations near L = 2.5 during the Halloween 2003 storm

Ground based recordings at Palmer Station, Antarctica (L = 2.44) provide rare observations of VLF waves at low L during and in the aftermath of the Halloween 2003 superstorms. VLF observations in the morning magnetic local time sector for Oct 29 to Nov 5 2003 are compared with daily global average changes in the electron radiation belts near the slot region. Wave activity observed at Palmer was remarkably intense during this period and included discrete chorus emissions, mid‐latitude hiss as well as an unusual form of hiss extending up to ∼15 kHz suggestive of auroral hiss. While the inner edge of the new radiation belt formed near L = 2, analysis of VLF data indicate that chorus was primarily confined outside L ≈ 2.75.

The oxygen isotopic composition of seawater during the Last Glacial Maximum

High-resolution oxygen and hydrogen isotope measurements were made on pore fluids from deep-sea sediments from sites in the North and South Atlantic. The data provide direct measurements of changes in the isotopic composition of bottom waters during the Last Glacial Maximum (LGM). Results from Ocean Drilling Program (ODP) Site 981 in the North Atlantic, currently bathed in North Atlantic Deep Water (NADW) reproduces previous results from the Ceara and Bermuda Rises, constraining the glacial–interglacial change in δ 18O of the deep Atlantic to be 0.7–0.8‰. Results from Site 984, which is located north of Site 981 and at a shallower water depth, yield a similar value (0.8‰), providing insight into the properties of Glacial North Atlantic Intermediate Water (GNAIW). Sites from ODP Leg 177 in the South Atlantic span the modern boundary between northern and southern sources of deep water. Data from the northern site (1088) yield a similar result to sites in the tropical and North Atlantic (0.7‰). At the southern site (1093), located south of the polar front, the change is substantially larger (1.1‰), representing the change in δ 18O of southern source waters since the LGM. These results confirm previous estimates that the global average change in δ 18O of seawater is 1.0±0.1‰. Hydrogen isotopes measured on pore fluids from three sites are consistent with the oxygen isotopes from these locations, giving further support to these results. At all sites studied, the temperature of the deep ocean during the LGM, calculated by combining the pore fluid results with oxygen isotope data from benthic foraminifera, was within 1°C of the freezing point of seawater.

Global Climate Change Ecosystems Effects

AbstractMuch concern is felt about global warming and many debates have ranged widely on this subject without as yet arriving at a precise answer; the 'best guess' at present is a 60% chance of a global average change in the 1·5–4·5 K range if carbon dioxide concentrations were to double. However, regional temperature changes are still more speculative depending on the heat retaining properties of the oceans and the continents. The reaction of ecosystems to climatic change is here illustrated by considering forests and birds, and it is concluded that the more rapid the climatic change, the higher the probability of disruption and surprise in the ecosystems affected. The author finally recommends the banning of chlorofluorocarbons and switching fuels from coal to natural gas thus buying time and slowing down global warming.

Changes in deep‐ocean water δ18O and temperature from the Last Glacial Maximum to the present

Estimates are made of changes of the oxygen isotope anomaly of deep‐ocean water and of deep‐ocean temperature for the Atlantic, Indian, and Pacific oceans from the time of the last glacial maximum to the present. Several independent sources of data, including oxygen isotope records of planktic and benthic foraminifera at selected core sites (primarily in the equatorial oceans), Climate: Long‐Range Investigation, Mapping, and Prediction sea surface temperatures estimates, and GEOSECS δ18O data for the present ocean water, are utilized together with the paleotemperature equation of Epstein et al. (1953). Glacial to interglacial change in oxygen isotope composition of the global deep‐ocean water is found to be −1.41 per mil compared with a global average change of −1.75 per mil for benthic foraminifera. The former value implies a sea level change between 128 and 141 m, depending on the choice of the isotope sea level conversion constant. A global deep ocean warming of 1.4°C from glacial maximum to the present is found from the above isotopic difference of 0.34 per mil. The consistency of the results in this paper with those of Chappell and Shackleton (1986) suggest that there is no significant contribution from isotopically light floating ice shelves surrounding Antarctica as proposed by Johnson and Andrews (1986), at least for the change from glacial maximum to the present. The ocean transition from glacial to interglacial episodes was accompanied by an estimated warming of 2.0°C in the Atlantic, 1.4°C in the Indian, and 1.1°C in the Pacific oceans. The glacial Pacific was colder than the Atlantic Ocean, but the difference between the two oceans was smaller than today.