Effects on Buildings, Infrastructure, and Services: In the Philippines, climate change impacts are expected to accelerate the structural fatigue and failure of physical infrastructure. 169 Extreme weather events have and will continue to cause severe damage to critical infrastructure,170 including most notably the national road network, Manila light rail transit system, port facilities, and power transmission systems.171 Flooding events could also severely impact schools, hospitals, and evacuation centers. 172 Decreased rainfall results in prolonged dry periods, which also adversely impact irrigation systems, water supply systems, and hydroelectric facilities, making water management a critical issue.173 III. Attribution of Impacts to Climate Change and Greenhouse Gases (Trenberth, Plan B, ClientEarth) The conventional approach to attribution of climate events is to characterize the event and ask (i) whether the likelihood or strength of such events has changed in the observational record, and (ii) whether this change is consistent with the anthropogenic influence as found in one or more climate models. This approach has had considerable success with extremes that are strongly governed by thermodynamic aspects of climate change, especially those related to temperature, each providing another independent line of evidence that anthropogenic climate change is affecting climate extremes.174 The conventional approach, however, is severely challenged when it comes to climate extremes that are strongly governed by atmospheric circulation, including local aspects of precipitation. It is inherently conservative and prone to false negatives, which underestimate the true likelihood of the human influence. In contrast to thermodynamic aspects of climate, forced circulation changes in climate models can be very non-robust, and physical understanding of the causes of these changes is generally lacking. 175 An approach that separates out the thermodynamic from dynamic effects may therefore be a fruitful way forward. This approach regards the circulation regime or weather event as a conditional state (whose change in likelihood is not assessed) and asks whether the impact of the particular event was affected by known changes in the climate system’s thermodynamic state (for example sea level, sea surface temperature, or atmospheric moisture content), concerning which there is a reasonably high level of confidence. 176 169 PHILIPPINES DEPARTMENT OF ENVIRONMENTAL AND NATURAL RESOURCES, THE PHILIPPINE STRATEGY ON CLIMATE CHANGE ADAPTATION 2010-2022 (2010). 170 See, e.g., WORLD BANK, PHILIPPINES TYPHOONS ONDOY AND PEPENG: POST-DISASTER NEEDS ASSESSMENT (2009) (finding that the damage to physical assets caused by the 2009 Ondoy and Pepeng typhoons reached Php 68.2 billion); WORLD BANK, CLIMATE RISKS AND ADAPTATION IN ASIAN COASTAL MEGACITIES: A SYNTHESIS REPORT (2010) (finding that the costs of future flooding in Manila, as exacerbated by climate change, could range from Php 5 billion to Php 112 billion). 171 GETTING A GRIP ON CLIMATE CHANGE IN THE PHILIPPINES, supra note 81, at 13. 172 PAGASA, supra note 78, at 49. 173 Id. 174 Trenberth brief, at pgs. 2-3; ClientEarth brief, at pgs. 38-39, n. 62. 175 Trenberth brief, at p. 3. 176 Id. at pgs. 3-4. 37