THE PHILIPPINES has long been prone to extreme weather, an unavoidable consequence of its geographical location.

But recent years have shown that our predicament is worsening for reasons outside just our place on the map. Five of the 10 deadliest typhoons to hit the country have occurred since just 2006 and, in a country of many coastal communities, we have seen thrice the global average in sea level rise.

Despite being among the lowest contributors to global greenhouse gas emissions, the Philippines is one of the most vulnerable to the impacts of climate change. Our development prospects are constantly threatened by climate-related disasters, while the vulnerability of our poor communities could well worsen with changes in precipitation, temperature, intensity of tropical cyclones, and frequency of extreme weather events.

Responding to the need for robust scientific assessments of the country’s climate, the Oscar M. Lopez Center for Climate Change Adaptation and Disaster Risk Management Foundation, Inc. (Oscar M. Lopez Center), took the lead in publishing the Philippine Climate Change Assessment.

The report is patterned after the Intergovernmental Panel on Climate Change (IPCC), the most authoritative scientific body for the assessment of global climate change. Because climate action can only be effective when it is understood at the local level, the report is a first attempt to come up with a comprehensive scientific assessment of climate change for the country, with the aim of both informing our country’s decision-makers and guiding our academe’s future research.

The actions we can take to prepare for the impacts of climate change are both numerous and far-reaching. “What is important is that every effort is grounded in localized, scientific basis,” says the Oscar M. Lopez Center’s Executive Director Mayan Quebral, “so that we can properly weigh the environmental and socio-economic consequences and come up with response strategies that are both realistic and successful.”

The report was produced in partnership with the Climate Change Commission (CCC), Filipino IPCC scientists, and other field experts. The first of three Working Group reports, the publication focuses on the physical science basis. It will be followed by “Working Group 2: Impacts, Adaptation, and Vulnerabilities”, and “Working Group 3: Mitigation of Climate Change,” both set to be released in 2017.

The “Physical Science Basis” report, the first assessment of three volumes of the Philippine Climate Change Assessment, covers the following topics: Global changes in climate; the Philippine climate; historical changes in the local climate; observed changes in the country’s ocean climate and sea level; drivers of local changes in climate; and projections of future changes in climate.

As a first attempt to come up with a comprehensive scientific assessment of climate change for the country, the publication’s goals are two-fold. First, by highlighting the most pressing and up-to-date knowledge on climate science, it aims to help the country’s decision makers create strategic climate response strategies. Second, it acts as a guide for future research by identifying the important gaps in the Philippines’ climate change science that our academe must strive to fill.

Below is a guide to the report’s key findings. The full report may be downloaded here.


Key Findings

  1. From 1951 to 2010, the annual mean temperature in the country increased by 0.65°C with a mean rate of 0.11°C per decade. In terms of temperature variability, more hot days and warm nights, and less cold days and nights have been observed over this period.
  2. The annual mean temperature for the tropical and maritime climate of the Philippines is 26.6°C, with high variability in rainfall influenced by large-scale systems (e.g., the northeast and southwest monsoons, tropical cyclones, El Niño Southern Oscillation [ENSO]) and local-scale systems (e.g., sea and lake breezes, urban heat islands).
  3. Observation records from 1951 to 2008 also indicate an increasing trend in the intensity and frequency of extreme rainfall events in many parts of the country, with significant increases observed in certain places such as Baguio, Tacloban, and Iloilo.
  4. On average, about 20 tropical cyclones (TC) enter the country every year, with the variation in yearly count driven by factors such as ENSO. Trends in TC frequency (or the number of TCs per year) indicate no appreciable increase in the observational record.
  5. Trends in sea surface temperature (SST) near the Philippines show that temperatures have been increasing by around 0.23°C ± 0.02°C per decade from 1981 to 2014. An estimate of the observed increase in global mean SST from 1979 to 2012 is 0.124°C ± 0.03°C for every decade.
  6. There is little available information on local sea level rise and as such, information on sea level rise for the entire country is limited.
  7. While global climate change is largely driven by GHG levels in the atmosphere, it is important to note the impacts of aerosols from biomass burning and pollution, land use and land cover change arising from agriculture and urbanization, and other such drivers on local climate and ecosystems, and their potential feedbacks on the greenhouse effect. The influence of the interplay between these local driving factors and GHGs on Philippine climate has yet to be examined.
  8. Future changes in Philippine climate relative to the baseline period (1971–2000) have been modelled for the 2020s (2006–2035) and 2050s (2036–2065) in response to various emission pathways. In one particular mid-range emission scenario (A1B of the IPCC SRES Scenarios), climate projections indicate increases in annual mean temperatures ranging from 0.9°C to 1.1°C in the 2020s and 1.8°C to 2.2°C in the 2050s.
  9. The dry season (March–May) is projected to be drier over most areas. The wet or southwest monsoon season (June November) will likely be wetter with rainfall increase ranging from 0.9% to 63% for Luzon and 2% to 22% for Visayas. Rainfall is projected to decline over Mindanao during this same season.
  10. Rainfall during the northeast monsoon season (December–February) is also projected to increase, particularly over the eastern part of the country.
  11. In general, by 2020 and 2050, dry days are likely to be more frequent over the Philippines, with more heavy rainfall days expected over Luzon and Visayas.
  12. This report identifies many areas that need further examination, such as the influence of large-scale climate drivers (e.g., ENSO, the Madden-Julian Oscillation, the Pacific Decadal Oscillation) on Philippine climate, the effect of sea level rise on saltwater intrusion and storm surges along coastal areas, and local climate impacts of aerosols and land use change, as well as their interaction with the enhanced greenhouse effect. However, such studies require reliable long-term observation records with adequate spatial coverage that is representative of local climate in the country.
  13. Local researchers are strongly encouraged to publish their work not only to contribute to the global pool of scientific knowledge, but more importantly to provide information and insight that can be used by policymakers to make well-informed, strategic decisions.


Directions for Future Studies

The Philippine Climate 

  1. While there have been attempts to analyze the complex interactions and feedbacks, such as those between tropical cyclones and monsoon rainfall events, these studies tend to be based on particular cases rather than seen in a climatological context. The comprehensive understanding of the role of these large-scale climate drivers (e.g., ENSO, MJO, PDO) and their interactions in determining Philippine climate is important if we are to have a fuller picture of climate change and its different driving forces, such as the radiative forcing caused by rising levels of anthropogenic greenhouse gases.

Historical Changes in Philippine Climate 

  1. In the Philippines, the physical science assessment of climate change is a challenge. Assessment of observational evidence of climate change and trends is constrained by the limited number of observing stations across the country and the fact that the current observing network does not adequately represent the diversity of local climates across the country.
  1. Efforts can be directed to the analysis of an older set of historical observations made in the late 19th to the early 20th century, since analysis of longer datasets can discern significant change over time.
  1. In view of the observational, analytical, and modeling work done in various places such as the national meteorological/hydrological agency, academic institutions, and the different national and local research centers, there is need for a mechanism to collate, integrate, and transform all the work into different sets of outputs that will be relevant for impact assessments, adaptation and mitigation planning, and knowledge management.

Observed Changes in Ocean Climate and Sea Level in the Philippines

  1. Analyzing records of existing tide gauges and correlating these to sea surface height (SSH) measurements will help in refining relative sea level change trends in the areas of the tide gauges and help identify local drivers of sea level change. Installation of additional tide gauges in areas with fastest rates of sea level rise based on SSH data should be recommended to NAMRIA.
  1. Local researchers can be encouraged to publish their paleo-SST and SLR in different locales in the country. Such studies can be prioritized in areas where human and ecological communities are projected to be highly vulnerable.
  1. Possible topics for future study include the relative significance of local groundwater extraction and land subsidence on sea levels, and the effect of SLR on saline intrusion and storm surges along coastal regions.

Drivers of Local Changes in Climate

  1. It is important to understand the relative contributions of Land use/land cover change (LULCC) and GHG increase on climate change because of their feedbacks on each other, where one can potentially amplify or attenuate the other. However, this interplay between LULCC and GHG increase has yet to be examined for the Philippines.
  1. There are ongoing but limited efforts to understand the impacts of urbanization on Philippine local climates. In addition, the local climate impacts of aerosols still need to be further examined. It is therefore recommended that these research areas be pursued to better understand and quantify local-scale drivers, particularly for urban areas in the country.

Projections of Future Changes in Climate

  1. It is important to enhance the modeling capacities in the country and to sustain activities that generate ensembles of model output to narrow down uncertainties in climate projections. The generation of worst and best case scenarios will guide the country’s disaster risk reduction and climate change adaptation efforts. Further studies can explore how to quantify the uncertainties involved in these projections and the implications on impact assessments.
  1. There is also a need for a deeper and more comprehensive analysis on how the underlying physical and dynamical processes in the climate system will evolve in the future.