Based on statistical analyses and Arctic Oscillation (AO) and the Pacific-North American pattern (PNA) induced climate anomalies in the 2001–2020 interval, it has been found that these climate modes drastically influence the fire danger (PFIv2) in differing ways across coastal and inland regions. The AO induces higher fire risk in northern Eurasia and central North America, whereas the PNA increases the fire danger across southern Asia and western North America. Moreover, fires have been predominantly identified, up to 70%, during the positive phases of AO and PNA northward of 50°N, in particular over Alaska, Baltic States and eastern Asia. For coincident positive AO and negative PNA days, a large number of fires have been identified over northwestern North America and northern Eurasia. Spectral analyses demonstrate that weather anomalies related to AO and PNA lead fire danger by 10–20 days, and both modes are significantly correlated to PFIv2 over north America and most of Eurasia. Despite some drawbacks related to the fire danger methods currently applied (PFI and FWI), it is demonstrated that the influence of AO and PNA on potential environmental driven-fires can be anticipated, in some locations on almost 90% of days. Fire danger forecasts are urgently needed and the understanding of factors and conditions, which are able to modify the environmental susceptibility to fire development, are crucial for adequate management to reduce the harmful effects of fire. In this sense, our results reveal that a better prediction of the fire season can be achieved by advanced assessment of the PNA and AO behavior, and shed light on the need to investigate the impact of other modes of climate variability upon wildfire frequency and severity.

The analysis of gross primary production (GPP) is crucial to better understand CO₂ exchanges between terrestrial ecosystems and the atmosphere, while the quantification of water-use efficiency (WUE) allows for the estimation of the compensation between carbon gained and water lost by the ecosystem. Understanding these dynamics is essential to better comprehend the responses of environments to ongoing climatic changes. The objective of the present study was to analyze, through AMERIFLUX and LBA network measurements, the variability of GPP and WUE in four distinct tropical biomes in Brazil: Pantanal, Amazonia, Caatinga and Cerrado (savanna). Furthermore, data measured by eddy covariance systems were used to assess remotely sensed GPP products (MOD17). We found a distinct seasonality of meteorological variables and energy fluxes with different latent heat controls regarding available energy in each site. Remotely sensed GPP was satisfactorily related with observed data, despite weak correlations in interannual estimates and consistent overestimations and underestimations during certain months. WUE was strongly dependent on water availability, with values of 0.95 gC kg⁻¹ H₂O (5.79 gC kg⁻¹ H₂O) in the wetter (drier) sites. These values reveal new thresholds that had not been previously reported in the literature. Our findings have crucial implications for ecosystem management and the design of climate policies regarding the conservation of tropical biomes, since WUE is expected to change in the ongoing climate change scenario that indicates an increase in frequency and severity of dry periods.

Satellite-based hot-spot analysis for the Pan-Arctic, shows that Asia experiences a greater number of fires compared to North America and Europe. While hot spots are prevalent through the year in Asia, Europe (North America) exhibits marked annual (semi-annual) variability. The Potential Fire Danger index (PFIv2) demonstrates increased fire incidence vulnerability across the Arctic and extra-tropics. Though not significant in northwestern North America and eastern Asia, significant-positive trends across the mid-latitudes of Eurasia and Siberia are clear. PFIv2 accurately matches the regional distribution of observed fires, while the worldwide used Fire Weather Index does not. Fire danger has evolved as distributions of short-interval precipitation events and background vegetation characteristics change. In conjunction with increased population and expanded infrastructure, frequent extreme events may increase pressure for new settlements that lead to greater fire exposure across the Pan-Arctic. Thus, PFIv2 may be useful for decision planners and danger managers to anticipate and minimize the adverse effects of indiscriminate fire use.

Among Mediterranean regions, the South-Central Zone of Chile (SCZCh) portrays a landscape where wildfires constantly and historically occur, many times damaging ecosystems, lives and livelihoods. Since 2010, this zone has entered a period of unprecedented drought that has contributed to wildfire rising trends. Wildfire occurrence and intensity in this zone can be associated with three main factors: climate and land cover as conditioning factors, and human activity as a triggering factor. This paper evaluates wildfire hazard for the SCZCh, based on environmental susceptibility to wildfire occurrence, using numerical regional climate and wildfire modeling for the 2002–2005 historical period and for the mid and late 21st-century under the RCP8.5 climate change scenario. Results indicate high skill in matching spatial patterns of fire spot occurrence and density in the historical period, as well as the ability to simulate seasonal behavior in wildfire environmental susceptibility, consistent with national historical statistics. The fire hazard in SCZCh will slightly increase in all seasons for both 2041–2050 and 2091–2100 periods, especially southward, with a long-term spatial homogenization of medium levels of hazard in Central Valley and Coastal Range, between 0 and 1000 m a.s.l. These results combined with the current homogeneous extensive exotic species plantations dominated by inflammable tree species in SCZCh might facilitate the occurrence of large wildfires under the projected 21st-century climate regime.

Fire incidence has been linked to multiple factors such as climate conditions, population density, agriculture, and lightning. Recently, fire frequency and severity have induced health problems and contributed to increase atmospheric greenhouse gases. Based on atmospheric susceptibility to fire, this study evaluates the use of a Potential Fire Index (PFIv2) to identify regions prone to fire development, as demonstrated by the satellite detected‐fire in the 2001–2016 interval. It is demonstrated that PFIv2 delivers an efficiency by up to 80% in matching the observed fires from Terra/MODIS satellite. The PFIv2 is also able to reproduce more accurately areas with fire activity with respect to its previous version, the PFI. This better performance is linked to the implementation of parameterization of water pressure deficit and atmospheric stability in the lower troposphere, and a new term to represent the effect of surface temperatures, particularly in mid‐latitudes and extra‐tropics. To evaluate the performance of the PFIv2 in more details, its comparison to MODIS burned areas demonstrated correlations values higher than 0.6 over the most susceptible regions such as Africa and South America, slightly lower correlation is found where fire does not primary follows the climate annual cycle, and is dominated by high frequency events. These findings indicate that the PFIv2 can be an important tool for decision makers in predicting the potential for vegetation fires development and fire danger.